North  Carolina  Board  of  Health 


Sanitary  Engineering. 


SECOND  EDITION. 


By  WILLIAM  CAIN,  C.  E. 

Member  of  the  North  Carolina  Board  of  Health. 


THE  LIBRARY  OF  THE 

•SEP  2 6 1942 

'UNIVERSITY  OF  ILLINOIS 


RALEIGH  : 

P M.  HALE,  and  EinVAEDS,.BEQrGHTON  & 00 
State  Printers  and  Binders. 

1 , 1380. 


North  Carolina  Board  of  Health. 


Sanitary  Engineering. 

SECOND  EDITION. 


By  WILLIAM  CAIN,  O.  E. 

Member  of  the  North  Carolina  Board  of  Health. 


THE  LIBRARY  OF  THE 
RALEIGH  : SEP  2 6 1942 

P.  M.  HALE,  and  EDWARDS,  BROUGHTON  & CO., 

State  Printers  and  Binders.  UNIVERSITY  CF  ILLINOIS 


Digitized  by  the  Internet  Archive 
in  2017  with  funding  from 

University  of  Illinois  Urbana-Champaign  Alternates 


https://archive.org/details/sanitaryengineer00cain_0 


2(oS>  li.tfiA/.C.w 


ClXs 


SANITARY  ENGINEERING. 

SECOND  EDITION. 


By  WILLIAM  CAIN,  C.  EL 


CHAPTER  I. 

GENERAL  CONSIDERATIONS. 

Death  rates  lowered  by  sanitary  works.— We  are 

told  upon  the  best  authority  that  in  England  there  occurs 
annually  upwards  of  four  million  cases  of  preventable  sick- 
ness; and  that  125,000  persons  are  premature  cut  off  every 
year  from  a neglect  of  sanitary  precautions. 

Now  if  this  be  true  in  a country  which  has  adopted  the 
best  known  sanitary  precautions,  at  great  expense,  how  much 
more  significant  will  the  records  in  this  State  appear, 
where  the  only  outlay  that  may  be  classed  under  the  head 
“ sanitary/’  is  generally  made  in  meeting  doctors ’ bills  and 
funeral  expenses . 

It  is  further  stated  that  in  England,  since  the  sanitary 
precautions  have  been  instituted,  that  the  death  rate  has 
been  lowered  by  from  one-fourth  to  one-third,  and  is  besides 
decreasing  from  year  to  year.  The  following  table,  refer- 
ring to  a few  localities  in  England,  taken  from  Latham’s 
“ Sanitary  Engineering,”  speaks  more  forcibly  than  all  the 
other  arguments  that  may  be  presented,  especially  to  those 
who  have  paid  but  little  attention  to  sanitary  subjects,  and 
are  inclined  to  be  skeptical  as  to  the  great  actual  saving  of 
life  that  may  be  attained.  I presume  the  table  is  made  out 


I 20  I 300 


4 


SANITARY  ENGINEERING. 


for  1873,  the  date  of  the  publication,  and  that  the  “ works  ” 
are  of  the  “ water  sewerage  ” kind  : 


Name  of  Place. 

Population 

in 

1861. 

1 Average  mor- 

1 tality  per  1 ,000 

before  con’tion 

1 of  works. 

Average  mor- 

tality per  1.000 

1 since  comple’n 

( of  works. 

Saving  of  life.?] 

Per  cent. 

Reduction  of 

typhoid  fever. 

Rate  per  cent 

Reduction  in 

rate  of  phtyisls. 

Per  cent. 

Banbury, 

10.238 

23.4 

20.5 

12* 

48 

41 

Cardiff, 

32,954 

33.2 

22.6 

32 

40 

17 

Corydon, 

30,229 

23  7 

18.6 

22 

63 

17 

Dover, 

23.108 

22.6 

20.9 

7 

36 

20 

Ely, . 

7,847 

23.9 

20.5 

14 

56 

47 

Leicester, 

68,056 

26.4 

25.2 

4* 

48 

32 

Macclesfield, 

27,475 

29.8 

23.7 

20“ 

48 

31 

Merthyr, 

52,778 

33.2 

26.2 

18 

60 

11 

Newport, 

24,756 

31.8 

21.6 

32 

36 

32 

Kugby 

7,818 

19.1 

18.6 

2* 

10 

43 

Salisbury, 

9.030 

27.5 

21  9 

20 

75 

49 

Warwick,  

10,570 

22.7 

21 

n 

52 

19 

A previous  statement  would  indicate  that  the  death  rate 
is  still  being  steadily  lowered.  As  Latham  states,  the  most 
healthy  districts  show  but  a small  saving  compared  with 
the  others ; though  nearly  all  show  a marked  diminution 
in  certain  diseases — typhoid  fever  and  phthisis. 

Similar  results  have  attended  the  enforcement  of  sanitary 
measures  in  some  of  our  American  cities. 

A striking  illustration  is  St.  Louis,  where,  it  is  stated, 
that  from  1867  (when  the  Board  of  Health  was  organized,)  to 
1877,  although  the  population  had  more  than  doubled,  the 
death  rate  had  decreased,  so  that  actually  in  1877  there  were 
fewer  deaths  than  in  1867. 

The  average  mortality  for  this  country  is  about  20,  rang- 
ing from  17  to  30  in  1,000  generally;  but  St.  Louis  shows  a 
death  rate  of  only  11,  which  apart  from  its  site,  “ must  be 
ascribed  largely  to  its  excellent  water  supply  and  sewer 
system.” 

Economical  Aspects. — Apart  from  the  humanitarian 
view  of  this  question,  it  may  be  considered  in  its  economi- 


GENERAL  CONSIDERATIONS. 


5 


cal  aspects : thus  Latham  has  taken  Croyden,  where  the 
total  cost  of  sewers,  &c.,  was  $943,800,  and  estimated  the 
saving  in  funerals,  in  sickness  (allowing  that  for  every  life 
saved  25  would  escape  sickness,  the  saving  being  estimated 
at  $5  for  every  sick  person,)  and  in  the  labor , for  6J  years 
only,  by  the  prevention  of  premature  death,  at  a total  of 
over  $1,000,000,  which  thus  exceeds,  in  the  short  space  of  6J 
years,  the  total  cost  of  the  sanitary  works. 

Yellow  Fever  caused  by  Filth. — How  much  more 
striking  would  be  the  result,  were  we  to  take  some  of  our 
own  plague  stricken  cities  in  America!  Where  has’ the  yellow 
fever  its  origin f In  the  filthiest  port  in  the  world,  Havana, 
where  ‘‘the  tide  being  almost  imperceptible,  all  the  empty- 
ings of  the  sewers  remain  in  the  harbor  until  they  become 
a foetid  and  revolting  mass  of  corruption.”  From  there 
the  seeds  of  the  yellow  fever  are  carried  by  ships  to  other 
ports  ; and  when  these  are  foul,  the  scourge  begins. 

Gen.  Butler  at  least  has  the  merit  of  having  to  a great 
extent  kept  New  Orleans  clean  and  free  from  the  epidemic 
during  his  occupancy  of  the  city.  In  1878,  however,  in 
consequence  of  the  foulness  of  the  city,  she  suffered  the 
most  terrible  visitation ; whilst  in  1879,  through  the  ener- 
getic workings  of  some  of  her  most  public  spirited  citizens, 
in  carrying  out  sanitary  measures,  the  mortality  from  yellow 
fever  was  very  much  reduced. 

Galveston  was  kept  clean  and  escaped  the  plague.  Hunts- 
ville, Ala.,  actually  sheltered  yellow  fever  victims  with  im- 
punity ; whilst  Memphis  in  1879  again  suffered  from  her 
foulness. 

What  more  instructive  lesson  than  the  facts  just  given? 

Advantages  of  Keeping  Clean.— If  we  keep  clean 
there  is  less  chance  of  dying,  greater  enjoyment  of  life  from 
increased  health,  fewer  bereavements  and  a positive  pecu- 
niary gain  to  the  community,  even  including  the  cost  of 
sanitary  works.  Health,  population,  and  money  values 
also,  generally  go  hand  in  hand,  when  other  conditions  are 
avorble. 


6 


SANITARY  ENGINEERING. 


On  the  contrary,  if  we  disobey  the  Divine  Will,  by  run- 
ning counter  to  natural  laws,  we  are  punished  for  the  sin 
of  disobedience.  Here  we  have  rewards  and  punishments — 
both  teaching  their  own  moral  lessons.  Choose  between 
them. 

Is  North  Carolina  Clean? — Let  us  now  inquire  as  to 
our  own  cleanliness,  which,  the  good  book  tells  us,  is  next 
to  Godliness.  The  result  of  this  inquiry  would  be,  that 
typhoid  fevers,  diphtheria  and  certain  enteric  fevers  that 
are  now  classed  as  “filth  diseases ,”  are  common,  especially  in 
the  larger  towns  of  the  State ; and  that  these  diseases  are 
sufficiently  accounted  for  by  bad  wells,  foul  yards , privies,  and 
cess-pools;  the  latter  tainting  the  air  with  their  gases  and 
the  water  with  their  dissolved  impurities. 

There  are  but  few  privies  in  the  State  that  ought  not  to 
be  abolished,  and  some  good  system  substituted  in  their 
place.  It  is  one  object  of  this  paper  to  suggest  such  systems. 

But  it  is  not  sufficient  that  our  own  house  alone  be  free 
from  reproach.  The  individual  may  suffer  when  it  is  only 
his  neighbors  who  are  to  blame.  The  whole  community, 
as  a unit,  must  practice  cleanliness. 

The  germ  of  disease,  engendered  amid  the  surroundings 
of  filth,  if  wafted  to  the  palace,  can  strike  as  deadly  a blow 
there  as  in  the  dirty  hovel,  as  recent  examples  show. 

Filth  and  Disease  go  hand  in  hand.— Of  the  exact  na- 
ture of  the  poison  generated  by  filth  we  know  little ; but  it 
has  certainly  been  demonstrated  in  numerous  cases  that  the 
ravages  of  epidemics  are  in  direct  proportion  to  the  foulness 
of  the  locality.  Thus  in  one  city,  diphtheria  followed  the 
line  of  bad  severs,  in  another  of  bad  wells.  Bad  water 
is  one  of  the  most  efficient  agents  in  spreading  disease. 

The  cholera  of  1853,  in  London,  attacked  districts  fur- 
nished with  unfiltered  Thames  water  with  3J  times  the 
severity  experienced  by  neighboring  districts  supplied  with 
Thames  water  filtered  through  sand  and  charcoal. 


GENERAL  CONSIDERATIONS. 


7 


It  has  become,  as  it  were  an  accepted  truth  in  sanitary 
science  that  the  fatal  effects  of  epidemics  may  either  be  pre- 
vented, or  their  spread  materially  hindered  by  a proper  at- 
tention to  sanitary  precautions.  These  precautions  simply 
consist  in  the  having,  at  all  times,  pure  air , wholesome  food, 
and  good  water.  It  is  only  the  first  and  last  of  these  requi- 
sites that  will  be  considered  in  what  follows,  as  they  per- 
tain more  especially  to  the  science  of  “Sanitary  Engineer- 
ing;” though  it  is  to  be  observed  that  wholesome  food  is  to 
to  a certain  extent  dependent  upon  the  good  water  or  milk 
used  in  the  cooking. 

By  a disregard  of  these  prerequisites  to  health — and  they 
are  more  or  less  disregarded  by  us  all — we  enfeeble  the  sys- 
tem, suffer  a loss  of  vital  energy,  and  are  thus  fit  subjects 
for  an  attack  by  the  first  epidemic. 

The  “ debilitating  effects”  of  large  cities  are  mainly  due 
to  the  poisonous  gases,  generated  by  the  putrid  matter  of 
sinks,  sewers,  &c.,  which  gases  find  their  way  into  chambers 
through  faulty  pipes  and  traps,  or  are  otherwise  diffused 
through  the  atmosphere.  When  the  debilitated  person 
seeks  the  pure  water  and  bracing  air  of  the  mountains,  the 
relief  is  almost  instantaneous,  thus  proving  the  life-giving 
qualities  of  pure  air  and  pure  water. 

The  Science  of  Prevention. — The  Science  of  Medicine, 
so  long  confined  to  the  art  of  healing  alone,  now  declares  in 
favor  of  the  Science  of  Prevention  as  the  higher  philosophy. 

Let  us,  then,  state  the  principles  of  this  latter  science 
clearly  and  succinctly  ; not  entering  into  many  details,  but 
giving  mainly  those  principles  and  facts  that  should  be 
known  by  every  one.  Any  system  proposed  must  be  a sim- 
ple one — the  simplest  is  generally  the  best — to  meet  the 
needs  and  comprehension  of  all  classes. 

The  law  organizing  the  N.  C.  Board  of  Health  requires  a 
monthly  report  from  each  county  on  vital  statistics.  It  is 
of  great  importance  that  this  law  be  faithfully  carried  out, 


8 


SANITARY  ENGINEERING. 


so  that  the  effect  of  the  suggestions  given  below,  where  car- 
ried out,  may  be  ascertained. 

The  same  act  requires  that  the  Board  “ shall  gather  in- 
formation, for  distribution  among  the  people,  with  the 
especial  purpose  of  informing  them  about  preventable  dis- 
eases/’ 

Disease  may  be  prevented,  other  conditions  being  favor- 
able, by  a proper  attention  to  drainage , ventilation , water  sup- 
ply, and  the  prompt  disposition  of  sewage  matters. 

We  shall  consider  the  subject  in  the  above  order. 


DRAINAGE. 


9 


CHAPTER  II. 

DRAINAGE. 

Wet  and  Dry  Soils. — The  farmer  well  knows  that 
when  a wet  soil  is  not  drained,  valuable  plants  refuse  to 
grow,  due  to  the  land  being  “cold”  and  “sour;”  and  that 
by  drainage  such  lands  are  often  converted  into  the  best 
quality  of  lands,  owing  to  the  replacement  of  the  excess  of 
water  and  vegetable  acids  by  warm,  dry  air,  so  that  the 
roots  now  find  the  proper  amount  of  air,  moisture  and  tem- 
perature to  satisfy  the  conditions  of  growth. 

The  sun’s  rays  now  cause  a healthy  decomposition  of  or- 
ganic substances,  in  place  of  the  imperfect  one  that  seems 
the  necessary  concomitant  of  moisture  in  excess ; so  that 
now  neither  acids  are  formed  in  the  ground,  nor  dangerous 
organic  impurities  thrown  off  into  the  air. 

It  is  the  latter  that  produce,  indirectly  or  otherwise,  the 
intermittent  and  remittent  fevers,  so  common  over  the  whole 
South.  The  best  cure  is  drainage. 

“ The  fens  of  Lincolnshire,  in  England,  and  marshy  dis- 
tricts along  the  lower  Thames  were  formerly  greatly 
scourged  with  fever  and  ague  and  with  malarial  neuralgia. 
The  extensive  drainage  operations  carried  on  in  these  dis- 
tricts have  had  the  effect  of  removing  these  ailments  en- 
tirely.” 

Where  ground  is  water-logged,  it  is  unfit  for  human  hab- 
itation. 

Drainage  is  especially  necessary  where  sewers  are  laid,  as 
the  sewer  gases  readily  penetrate  the  brick  walls  of  the 
sewers,  and  then  find  access  to  cellars,  etc.  A dry  soil  will 
condense  enough  oxygen  to  burn  these  gases  up,  as  will  be 
more  fully  explained  further  on. 

MalariaT  Poison. — It  is  generally  believed  that  all 
damp  places,  as  most  ponds,  marshes,  swamps,  river  bottoms 
subject  to  overflow,  etc.,  portions  of  which; along  the  banks,  are 


10 


SANITARY  ENGINEERING. 


alternately  wet  and  dry , are  such  as  originate  malarial  poison, 
and  must  continue  to  originate  it  so  long  as  such  conditions 
hold.  The  occasional  overflow  of  salt  water  aggravates  the 
evil,  as  also  the  accumulation  of  leaves,  decaying  wood,  etc., 
especially  where  thick  vegetation  causes  a stagnation  of  the 
air,  with  dense  shade.  It  is  obviously  correct  then  to  cut 
down  such  vegetation  immediately  around  the  damp  lo- 
cality, drain  it  and  put  it  under  cultivation.  If  the  rise  and 
fall  of  the  water,  in  the  pond  or  marsh,  alternately  covers 
and  exposes  much  of  the  banks — i.  e.,  if  the  banks  are  not 
vertical,  or  made  so — then  the  body  of  water  must  be  en- 
tirely drained  off,  if  possible ; otherwise  the  injurious  de- 
compositions due  to  wet  soils  will  continue  to  go  on  and 
breed  malaria.  It  is  found  that  winds  can  transport  malaria 
some  miles.  It  is  therefore  best  not  to  cut  down  open  forests 
at  a little  distance  from  the  damp  localities,  as  they  inter- 
cept the  malaria  to  a considerable  extent. 

It  is  very  often  the  case  that  dwelling  houses,  in  city  and 
country  both,  are  surrounded  with  such  a dense  mass  of 
shrubbery  (perhaps  intended  to  satisfy  the  sesthetic  taste) 
as  to  cutoff  both  fresh  air  and  sunshine;  thus  rendering 
the  house  and  yard  damp  and  the  air  impure.  Such  vaults 
should  be  rendered  habitable  by  the  free  use  of  the  axe.  It 
is  not  well  to  have  too  much  shade  in  our  cities;  pure  air 
and  sunshine  are  the  best  purifying  agents  we  have.  It  is 
a custom  (but  rarely  “ honored  in  the  breach”)  to  deny  earn- 
estly and  with  many  asseverations  that  malaria  affects  the 
locality  one  lives  in.  Sad  must  be  the  condition  of  that 
person,  who,  even  if  he  admits  an  occasional  malarial  fever, 
cannot  point  out  another  locality  where  the  malady  is  in- 
finitely more  distressing. 

Acting  upon  this  recognized  principle,  it  is  suggested  that 
whilst  the  mountains  and  hilly  regions  hardly  ever  originate 
fever  and  ague,  that  much  of  the  remainder  of  the  State  is 
subject  to  it  to  a greater  or  less  extent,  and  therefore  that 
thorough  drainage  is  one  of  the  first  requisites  to  increased 


DRAINAGE. 


11 


healthfulness.  Whilst  thinly  settled  districts  may  not  be 
able  to  institute  proper  precautions,  yet  the  larger  towns 
can  drain  the  ponds,  low  places,  roads  and  mother  earth 
generally  in  their  vicinity. 

In  the  last  column  of  the  previous  table  is  seen  the  re- 
duction in  the  death-rate  from  phthisis  of  twelve  English 
towns.  “ This  saving  of  life  is  ascribed  to  the  effect  of 
drainage  works  in  drying  the  subsoil  of  those  places.” 

In  this  State,  Salisbury  may  be  given  as  an  instance 
where  the  drainage  of  a large  pond  near  the  town  has  very 
largely  diminished  the  prevalence  of  malarial  fevers. 

Subsoil  Drainage. — In  the  subsoil  drainage  of  streets 
and  roads,  covered  drains , formed  of  rock  or  tile,  should  be 
used  in  preference  to  open  drains.  Open  drains,  unless  the 
soil  is  very  tenacious,  and  can  stand  at  a steep  slope,  take 
up  too  much  space.  Besides  they  are  constantly  needing 
repairs  and  often  hold  stagnant  water  and  decayed  filth  ; so 
that  in  some  countries  their  courses  have  been  marked  by 
excessive  ravages  of  cholera  over  adjoining  districts. 

A given  tract  of  land  is  best  drained  for  agricultural  pur- 
poses by  stone  or  pipe  drains  of  1 to  2 inches  diameter,  run- 
ning straight  down  the  hillsides  (when  not  too  steep),  in 
parallel  rows,  25  to  50  feet  apart,  and  30  to  36  inches  below 
the  surface.  These  small  drains  discharge  into  larger  in- 
tercepting drains,  run  down  the  hollows;  and  these,  in  turn, 
empty  into  larger  drains  (that  may  often  be  open),  that  fol- 
low the  courses  of  the  valleys  and  perhaps  serve  as  the 
water  channels  of  small  streams.  Such  draining  necessarily 
ensures  a deep,  mellow  soil,  that  not  only  satisfies  the  needs 
of  agriculture,  but  is  in  perfect  keeping  with  the  require- 
ments of  health.  Towns  should  at  least  keep  the  subsoil 
dry,  by  covered  drains  run  along  the  streets  and  elsewhere, 
at  sufficient  depths  to  drain  the  cellars  thoroughly  and  to 
prevent  standing  pools  of  water. 

Tile  drains  2 inches  in  diameter,  under  the  side-ditches, 
or  one  3-inch  drain  under  the  middle  of  the  road,  is  suf- 


12 


SANITARY  ENGINEERING. 


ficient  generally.  An  outlet  drain  should  run  from  the  de- 
pressions in  the  road.  A drain  or  culvert  crossing  the  road 
should  be  large  enough  to  pass  2 inches  of  rainfall  in  one 
hour  when  the  drainage  area  is  small,  1 inch  for  a valley 
two  to  three  miles  long,  and  so  on. 

All  streets  and  roads  should  be  built  higher  in  the  mid- 
dle than  at  the  sides,  and  should  have  gutters  deep  enough 
to  cany  off  storm  waters,  unless  there  are  specially  con- 
structed large  drains  for  this  purpose  (as  to  which  see 
“Water  Sewerage,”  further  on). 

Complete  Drainage. — If  such  drains  (designed  to  carry 
off  all  the  rain  water,  slops  and  waste  water  that  is  not  ab- 
sorbed by  the  ground,)  are  contemplated,  regard  must  be 
paid,  in  laying  them,  to  the  future  sewerage  of  the  town, 
even  if  this  is  not  carried  on  at  the  same  time  as  the  drain- 
age system  proper. 

The  drainage  of  large  districts,  swamp  lands,  low  lands, 
etc.,  varies  so  with  the  configuration  of  the  ground  that  it 
is  impossible  to  give  any  set  of  rules  that  apply  in  all  cases. 
As  a rule,  the  district  is  intersected  by  a number  of  dykes, 
often  parallel,  that  drain  into  larger  dykes  or  streams. 

Intercepting  dykes  are  often  dug  around  the  whole  area 
to  be  drained  to  prevent  the  access  of  water  from  without. 

As  an  illustration,  the  low  “ Landes  ” in  France  may  be 
given.  Here  260,000  acres  of  the  richest  lands  in  France 
have  been  reclaimed,  chiefly  by  cutting  open  canals  16  to 
20  feet  wide,  following  the  natural  slope  of  the  plateau  with 
a fall  of  1 to  2 per  1,000.  Of  these  canals  1,600  miles  have 
been  completed.  For  75  miles  along  the  coast,  huge  sand- 
banks protect  the  country  from  the  sea,  the  drainage  along 
them  being  received  by  a large  collecting  canal  40  feet  wide. 
The  works  cost  $1,700,000,  about;  and  the  value  of  the  re- 
claimed land  is  estimated  at  upwards  of  $56,000,000. 

“ The  fevers  which  formerly  ravaged  the  country  have  disap- 
peared, and  the  country  may  now  he  considered  one  of  the  most 
healthy  in  France 


DKAINAGE. 


13 


If  the  land  is  beneath  the  sea  level,  as  in  Holland,  then 
the  water  must  be  pumped  out  of  the  area,  the  latter  being 
protected  from  the  encroachments  of  the  sea  by  an  embank- 
ment. 

Straightening  the  course  of  rivers,  likewise,  is  efficient  in 
causing  increased  scour,  a lowering  of  the  bed  and  a lessen- 
ed liability  to  overflow. 

Ponds  are  easily  drained  by  simply  cutting  a ditch  of  the 
proper  size  through  the  natural  or  artificial  embankment 
surrounding  them.  The  greater  the  extent  of  the  water 
shed,  and  the  greater  the  rainfall,  and  the  imperviousness 
of  the  surface,  the  larger  of  course  is  the  ditch. 

The  so  called  “wet  weather  ” ponds,  often  on  high  ground, 
should  never  be  tolerated,  as  they  present  the  very  condi- 
tions for  fostering  malaria — a large  area,  alternately  wet  and 
dry.* 

The  natural  division  of  a country  for  drainage  purposes 
is  into  districts  belonging  to  the  same  water  shed,  bounded, 
of  course,  by  the  ridges  and  streams.  Considerable  incon- 
venience has  been  caused  in  some  thickly  settled  countries 
by  a disregard  of  natural  boundaries. 

The  extent  to  which  drains  exert  an  influence  on  the 
ground  on  either  side  depends  on  their  depth,  and  the  char- 
acter of  the  soil,  whether  very  retentive  or  porous.  Their 
action  is  analagous  to  that  of  wells  given  further  on,  except 
that  the  bottom  of  the  ditch  does  not  generally  reach  the 
level  of  complete  saturation  of  the  ground  as  is  often  the 
case  in  wells. 

It  is  best  not  to, open  new  ditches  from  “June  to  Novem- 
ber” in  malarial  districts,  unless  for  house  drainage.  Cel- 
lars should  be  drained  by  leading  a pipe  from  below  the 
bottom  of  the  cellar  to  some  convenient  exit  to  the  open  air 

♦See  Kerr’s  Geology  of  N.  C.,  (Introduction)  for  an  excellent  presenta- 
tion of  the  leading  topographical  features  of  the  State,  especially  its 
swamps  and  pocosins,  as  relating  to  the  matter  in  hand. 


14 


SANITARY  ENGINEERING. 


at  a lower  level;  or  similar  drains  may  be  laid  just  outside 
of  the  building. 

It  is  plain  that  greater  attention  should  be  paid  to  drain- 
age in  towns  near  our  sea  coast  than  in  the  hilly  regions,  as 
decomposition  is  generally  greater,  due  to  increased  mois- 
ture and  temperature,  not  forgetting  however  that  its  neg- 
lect anywhere  must  cause  pernicious  effects. 


VENTILATION. 


15 


CHAPTER  III. 

VENTILATION. 

The  Constituents  of  the  Air. — It  has  been  found  that 
in  certain  manufactories  and  machine  shops  that  the  air  is 
so  filled  with  certain  impurites  that  30  years  is  the  maxi- 
mum age  attained  by  the  operatives.  Such  instances  (and 
they  may  be  multiplied),  though  they  indicate  criminal 
neglect  in  the  management,  are  fortunately  exceptional,  and 
need  not  be  considered  here. 

The  impurities  that  we  shall  consider  under  this  head, 
as  concerning  ventilation,  result  from  the  breathing  of  men 
and  animals  and  the  burning  of  gas , oil , etc.,  in  illumination 
and  heating. 

Country  air,  wherever  analyzed,  is  found  to  contain  in 
volume  nearly  1*5  oxygen  to  4-5  nitrogen,  with  small  variable 
amounts  of  aqueous  vapor,  ammonia,  carbonic  acid  and 
certain  microscopic  organisms,  besides  dust,  etc. 

If  phosphorus  is  burnt  in  a bell  jar,  placed  over  water,  it 
combines  with  nearly  all  of  the  oxygen  in  the  confined  air, 
forming  white  fumes  of  “phosphorus  pentoxide,”  that  are 
soon  entirely  absorbed  by  the  water,  leaving  nearly  pure 
nitrogen  in  the  jar.  The  water  rises  so  as  to  fill  about  one- 
fifth  of  the  original  air  space  in  the  bell  jar,  thus  showing 
that  the  substance  (oxygen)  abstracted  is  nearly  one-fifth 
by  volume  of  the  whole.  The  gas  (nitrogen)  now  remain- 
ing in  the  jar  is  colorless,  inodorous,  and  does  not  support 
combustion  or  animal  life.  Pure  oxygen  gas,  (which  is 
readily  obtained  separately  by  heating  mercury  oxide  or 
potassium  chlorate,  etc.),  is  likewise  colorless  and  inodorous, 
but  it  supports  combustion  readily — iron  even  burning 
(oxidizing)  in  it  with  great  brilliancy. 

The  oxygen  is  the  life-giving  principle  of  the  air.  An  animal, 
however,  exposed  to  pure  oxygen  gas  is  over-stimulated  to 
such  an  extent  that  it  soon  dies.  The  nitrogen,  therefore , 


16 


SANITARY  ENGINEERING. 


acts  as  a diluent  of  the  oxygen,  and  it  is  found  that  the 
above  proportion  of  4 to  1 cannot  be  much  varied  from 
without  deleterious  consequences  ensuing.  The  oxygen  is 
not  chemically  combined  with  the  nitrogen,  it  is  simply 
mixed  with  it  as  sugar  is  dissolved  in  water — the  little  atoms 
of  the  one  penetrating  the  spaces  between  the  atoms  of  the 
other  without  destroying  the  transparency  of  the  medium. 

Dr.  Angus  Smith  has  made  a large  number  of  analyses  of 
air  in  various  parts  of  Great  Britain.  The  amount  of  oxy- 
gen by  volume  in  10,000  parts  of  air  are  given  for  various 
localities  as  follows : 


Mountain  air, 2099  parts. 

Towns  (average), 2096  “ 

Room  (rather  close), 2089 

Pit  of  a theatre,  11.30  P.  M., 2074  “ 

Backs  of  houses  and  closets, 2070  “ 


When  air  contains  only  1850  parts  of  oxygen  to  10,000  of 
air,  it  will  not  support  the  combustion  of  a candle,  neither 
will  it  support  life  long.  The  relative  densities  of  oxygen 
and  nitrogen  are  as  16  to  14,  so  that  an  average  composition 
of  air  by  weight  in  10,000  parts  is  oxygen  2310,  nitrogen 
7690. 

The  invisible  aqueous  vapor  exists  in  the  air  at  all  times 
in  various  quantities,  often  condensed  as  visible  clouds,  dew, 
etc.  Its  amount  varies  greatly  with  the  temperature. 
Thus  one  cubic  foot  of  air  at  90°  Fah.  can  hold  14.50  grains 
of  aqueous  vapor  as  invisible  gas ; whilst  air  at  the  freezing 
point,  32°  Fah.,  can  hold  only  2.37  grains  of  water  gas. 
The  air  in  both  cases  is  said  to  be  “saturated,”  since  it  can- 
not hold  any  more  water  gas,  as  gas ; any  excess  being  pre- 
cipitated as  rain,  or  formed  into  the  liquid  particles  consti- 
tuting fog  or  cloud  and  becoming  therefore  visible.  In  fact 
suppose  air,  saturated  at  90°,  to  be  cooled  down  to  32°  sud- 
denly: then  12.13  grains  of  rain  will  fall  for  every  cubic 


VENTILATION. 


17 


foot  of  air,  leaving  only  a little  over  one-seventh  of  the 
original  moisture  in  the  air!  It  is  upon  this  principle  that 
the  phenomena  of  rain,  dew,  etc.,  depend. 

It  will  have  been  noticed  by  those  who  read  the  daily 
reports  given  by  the  signal  stations,  that  there  is  a column 
marked  “relative  humidity.”  This  gives  the  per  centageof 
full  saturation  of  the  air  at  the  time  of  observation.  Thus,, 
“relative  humidity  60,”  would  indicative  that  the  air  con- 
tains 60  per  cent,  by  weight  of  the  water  gas  it  can  hold,, 
without  fog  forming. 

From  Kerr’s  Geology  of  North  Carolina,  p.  87,  we  find 
the  average  yearly  humidities  of  several  places  as  follows  : 
Wilmington  57,  Charlotte  65,  St.  Louis  67,  London  80  and 
New  Orleans  86;  the  first  two  giving  only  the  mean  from 
a little  over  one  years  observations.  Whilst  in  London  fog 
is  common,  on  the  coast  of  the  Red  Sea  a cloud  never  forms,, 
the  dryest  air  there  during  a simoom  containing  only  one- 
fifteenth  of  the  saturating  quantity. 

Now  it  is  well  known  that  excessive  moisture  is  deleteri- 
ous to  weak  throats,  lungs,  etc.  As  to  the  effect  of  extreme- 
dryness,  I am  not  informed,  save  that  these-little-red  hot- 
panting-cast  iron-stoves  produce  a bad  effect  on  the  air, 
which  is  very  much  ameliorated  by  evaporating  water  in 
vessels  placed  over  them.  The  bad  effect  must  be  due 
largely  to  the  drying  of  the  air.  Thus  to  take  our  previous 
example,  if  the  air  near  the  stove  is  heated  only  from  32°  to 
90°,  and  we  suppose  it  “saturated”  at  the  lower  temperature, 
then  at  the  higher  one  it  has  only  the  same  amount  of 
water  gas,  but  it  can  hold  nearly  seven  times  as  much ; and 
if  we  suppose  it  only  half  saturated  at  32,  then  at  90  it  will 
be  nearly  as  dry  as  the  air  of  a withering  simoom,  and  at 
highest  temperatures  much  dryer!  Such  extremes  cannot 
fail  to  be  unwholesome,  and  therefore  if  stoves  are  to  be 
used,  let  them  be  large  and  heated  as  little  as  will  give  the 
necessary  warmth. 


2 


18 


SANITARY  ENGINEERING. 


Another  important  constituent  of  the  air  is  ammonia , 
though  it  exists  in  comparatively  minute  quantities  (about 
1 in  1,000,000  of  air);  still  it  is  mainly  from  this  ammonia 
that  vegetables  obtain  the  nitrogen  necessary  to  form  their 
seeds  and  fruit.  It  is  given  off  from  urine  and  stable 
manure,  unless  gypsum  is  added  to  fix  it.  It  is  not  injuri- 
ous by  itself  in  small  quantities  and  need  not  be  further 
considered.  2 

The  most  important,  by  far,  of  the  inorganic  air  constitu- 
ents, next  to  oxygen,  is  carbonic  acid.  Its  amount  varies 
within  wide  limits;  thus  in  Scotland,  mountain  air  con- 
tained 3.2  at  top  of  mountain,  to  3.4  at  bottom,  in  10,000 
volumes.  In  London  it  varies  from  3 in  open  parks  to  3.4 
on  the  Thames,  and  4 as  a rough  average,  on  the  streets. 
In  Manchester,  the  amount  of  6.8  to  10,000  was  reached 
during  fogs,  wrhich  is  slightly  over  the  extreme  allowance 
considered  advisable,  which  has  been  fixed  by  some  at  6 in 
10,000  volumes.  Carbonic  acid  is  formed  by  the  chemical 
combination  of  carbon  with  oxygen.  Thus  when  wood, 
coal,  oil  or  gas  is  burnt,  carbonic  acid  is  formed.  It  is  also 
given  off  by  the  decay  of  wood,  in  certain  decompositions, 
and  in  the  breathing  of  animals.  In  fact,  if  the  air  in  ajar 
is  extracted  and  then  returned  from  the  lungs  into  the  jar 
again,  it  will  not  support  the  combustion  of  a candle, 
although  the  amount  of  carbonic  acid  expired  is  only  5 per 
cent.  The  lungs  and  body  likewise  exhale  organic  impuri- 
ties, about  in  proportion  to  the  amount  of  carbonic  acid 
throwm  off,  the  nose  readily  detecting  the  vitiation  due  to 
this  cause.  It  is  thought  by  many  that  these  organic  im- 
purities— fatty  matters  thrown  off  from  the  skin,  particles 
of  skin,  odors,  etc.,  from  man  and  beast — although  constitut- 
ing only  the  one  hundred  millionth  part  of  air  in  the 
country,  or  about  the  five  millionth  part  in  crowded  cars,  is 
still  the  most  dangerous  to  man  of  the  air  constituents;  for 
it  is  in  every  stage  of  decomposition,  and  must  furnish  food 
for  the  microscopical  denizens  of  the  air,  some  of  which  no 


VENTILATION. 


19 


doubt  are  scavengers,  but  others  are  thought  by  some  to 
cause  disease. 

The  Atmospheric  Germs. — It  is  well  known  now  that 
fermentation  and  certain  chemical  changes  are  brought 
about  by  minute  vegetable  or  animal  growths,  whose  natural 
habitat  is  the  air.  Tyndall  has  filtered  air  through  cotton 
wool  to  put  next  the  most  decomposable  substances,  and 
found  that  no  change  occurred  in  them,  whilst  common 
air  caused  decomposition  or  fermentation  to  begin.  These 
experiments  pretty  conclusively  disprove  the  theory  of 
“ spontaneous  generation.”  Whether  epidemic  diseases 
owe  their  origin  to  “atmospheric  germs  ” is  not  certainly 
known  as  yet,  but  thet  heory  is  at  least  plausible,  and 
explains  many  facts  more  fully  than  any  other  theory 
generally  known. 

We  know  this  much,  that  sewer  gas,  even  in  the  minutest 
quantity,  is  sometimes  fatal,  (which  is  not  due  to  the  chemi- 
cal gases  formed,  for  the  chemist  breathes  them  every  day), 
at  other  times  innocuous,  especially  when  free  ventilation 
has  been  secured.  Similarly  the  discharges,  and  even  gar- 
ments, of  patients  suffering  with  certain  fevers  can  com- 
municate the  disease.  Yellow  fever,  cholera,  small  pox, 
etc.,  is  transported  in  ships  by  mere  clothing.  These  facts, 
in  connection  with  the  fact  that  certain  organisms  in  the 
air  seem  to  follow  cholera  (as  was  shown  in  Germany,  and 
the  microscope  may  reveal  the  same  thing  in  connection 
with  other  epidemics),  seem  to  point  to  the  atmospheric 
germ  as  being  connected  intimately  with  certain  diseases. 
While  the  truth  is  being  worked  out  by  scientists,  let  us 
make  use  of  known  facts  and  proceed  to  “scotch  the  snake*’ 
wherever  its  presence  may  be  reasonably  suspected. 

Vitiation  of  the  Air  by  Breathing  and  Illumina- 
tion.— -It  is  found  that  a man  gives  off  somewhat  over  0-10 
of  a cubic  foot  of  carbonic  acid  per  hour ; that  a lamp  or 
two  lighted  candles  produce  the  same  amount,  and  that  a 
gas  jet,  burning  3 cubic  feet  of  gas  per  hour,  produces  as 


20 


SANITARY  ENGINEERING. 


much  carbonic  acid  per  hour  as  two  or  three  people.  It  is 
true  that  the  gas  gives  off  no  organic  impurities,  hut  if  not 
burning  brightly  the  poisonous  carbonic  oxide  is  always 
formed. 

If  we  adopt  6 volumes  in  10,000  as  the  safe  limit  of  the 
amount  of  carbonic  acid  to  air,  then  it  follows  that  for 
every  man  or  lamp  or  two  candles  in  a room,  we  must  sup- 
ply at  least  1,000  cubic  feet  of  pure  air  in  every  hour  to 
dilute  the  to  cubic  foot  of  carbonic  acid  formed.  A.  gas 
jet  will  require  two  or  three  times  as  much  pure  air. 

But  since  the  admitted  air  contained  carbonic  acid,  we 
must  supply  more  air  to  not  exceed  the  maximum  adopted  ' 
thus  if  the  admitted  air  contain  three  volumes  in  10,000  of 
carbonic  acid,  we  must  admit  2,000  cubic  feet  for  every  per- 
son, since  the  6-10  of  carbonic  acid  admitted,  added  to  the 
6-10  expired  per  hour,  gives  the  ratio  of  12  to  20,000  or  6 to 
10,000  allowed. 

It  is  said  by  some,  that  experience  in  hospitals  shows  that 
from  2,000  to  3,000  cubic  feet  of  fresh  air  should  be  admit- 
ted every  hour  for  each  individual;  whilst  again  we  are  told 
that  for  a healthy  person  in  a barrack  room  1,200  cubic 
feet  per  hour  will  suffice,  and  that  the  vitiation,  tested  by 
the  sense  of  smell,  for  hospitals  is  not  perceptible  when 
somewhat  less  than  the  2,000  to  3,000  cubic  feet  are  pro- 
vided. 

No  fixed  standard  has  thus  been  agreed  upon.  In  fact, 
it  doubtless  varies  with  the  climate  and  the  health  of  the 
person.  The  Laplander  can  breathe  impure  air  better  than 
we,  probably  because  the  organic  impurities  thrown  off  by 
him  are  not  so  readily  decomposed  as  in  our  warmer  air. 
The  carbonic  acid  formed  by  combustion  and  respiration 
being  heavier  than  air  at  the  same  temperature,  would  sink 
to  the  floor ; but  in  consequence  of  its  high  temperature,  it 
first  rises  to  the  ceiling ; so  that  as  much  as  60  to  70  parts 
of  it  in  10,000  of  air  has  been  found  at  the  top  of  an  ordinary 
sized  room  in  which  two  people  were  sitting  and  three  gas 


VENTILATION. 


21 


jets  burning.  At  the  same  temperature , however,  we  should 
expect  to  find  the  largest  amount  of  it  at  low  elevations,  thus 
vitiating  the  lower  strata  of  the  atmosphere,  or  room,  very 
greatly.  Fortunately,  however,  gases  have  the  power  of 
■“  diffusion,”  so  that  a heavy  gas  will  actually  rise  to  mix 
with  a lighter  gas-;  further,  it  will  pass  through  membranes 
and  thin  plates  of  stucco  to  effect  the  same  object,  so  that 
the  amount  of  carbonic  acid  is  not  generally  a function  of 
the  elevation  of  a locality. 

Where  a room  has  no  flue  or  chimney  to  keep  up  a con- 
stant circulation,  then  openings  should  be  provided  near 
the  top  of  the  room  to  let  the  warmer  impure  gases  out,  and 
not  let  them  cool  and  descend  again  to  vitiate  the  air  we 
breathe. 

Vitiation  by  Perspiration. — In  addition  to  the  carbonic 
acid  given  off  by  the  lungs  and  skin  of  a man,  there  is  ex- 
haled a considerable  degree  of  moisture,  generally  loaded 
too  with  organic  matter,  which  produces  smell.  The  amount 
has  been  estimated  at  from  1.5  pounds  to  2.5  pounds  per 
day  on  an  average.  A high  temperature,  or  exercise,  causes 
greater  perspiration,  thus  cooling  the  person  somewhat. 

The  amount  of  moisture  given  off  is  considered  by  some 
in  connection  with  the  carbonic  acid  exhaled,  to  ascertain 
the  theoretical  amount  of  air  to  admit;  but  this  theoretical 
amount  for  most  houses  is  larger  than  healthy  persons  seem 
to  require,  according  to  certain  experience.  This  is  account- 
ed for  by  the  fact  that  opening  doors  and  windows,  es- 
pecially if  they  are  kept  open  for  some  time,  the  draft 
through  cracks,  &c.,  add  very  much  to  the  volume  of  ad- 
mitted air,  though  nof  considered  in  the  computation. 

Lime  as  a Purifier. — If  a house  has  been  lately  plastered 
or  white-washed,  the  lime  will,  at  first,  take  up  the  carbonic 
acid  with  avidity  ; so  will  any  ordinary  mortar;  in  fact,  I 
have  seen  artificial  stone  made  by  passing  the  products  of 
combustion  of  a stove  (carbonic  acid  mainly)  by  a flue  into 
a room  where  was  placed  the  mortar,  moulded  into  the  re- 


22 


SANITARY  ENGINEERING. 


quired  form.  The  lime  of  the  mortar  changed  to  carbonate 
of  lime,  which  cemented  firmly  the  grains  of  sand  into  a 
hard  rock. 

It  destroys  organisms  to  whitewash.  It  would  seem,  there- 
fore, that  a plastered  wall  whitewashed  was  better  than  either 
the  “hard  finish”  or  papering.  The  accumulation  of  filth 
in  successive  coats  of  papering  in  old  houses  is  probably 
frightful.  Most  of  us  have  seen  the  trunks  of  trees  white- 
washed. This  seems  to  me  a misdirected  effort  to  promote 
health.  Why  should  such  indignity  be  practiced  on  our 
noblest  growths,  stopping  up  the  pores  of  the  bark  and 
probably  injuring  the  tree,  in  order  to  remove  a little  car- 
bonic acid  out  of  doors,  where  it  is  not  in  excess? 

The  Leaves  of  Plants  as  Purifiers. — The  carbonic  acid 
thrown  off  into  the  air  by  decomposition,  lighting,  heating 
and  the  breathing  of  animals,  is  taken  up  by  the  leaves  of 
growing  plants,  where  it  is  decomposed,  by  aid  of  the  sun’s 
rays;  the  carbon  being  appropriated  to  help  make  woody 
fibre,  &c.,  and  the  oxygen  being  given  back  to  the  air  to  fit 
it  for  respiration.  We  cannot  imitate  this  process  in  venti- 
lation schemes,  but  have  to  resort  to  heated  currents  or  to 
fans  to  expel  the  foul  air  from  our  rooms  and  leave  it  to 
nature  to  carry  the  foul  air  by  the  winds  to  her  millions  of 
laboratories  and  return  it  to  us  pure.  If  there  was  no  vege- 
table growdh,  however,  it  has  been  computed  that  the 
breathing  of  animals  would  not  vitiate  the  air  perceptibly, 
over  the  whole  globe,  in  some  thousands  of  years. 

Limit  to  Ventilation  Schemes. — It  is  impossible  to 
change  the  air,  with  comfort,  in  a room,  as  often  as  the  winds 
do,  out  of  doors;  but  we  can  easily  prevent  the  air  in  the 
rooms  from  becoming  too  impure  to  breathe.  Even  when 
there  is  no  special  attention  paid  to  ventilation,  it  is  found 
that  the  hotter  inside  air  is  going  out  continually,  through 
every  possible  outlet,  and  cool  fresh  air  coming  in  to  take 
its  place.  In  ve^  open  houses,  ventilation  is  often  secured 


VENTILATION. 


23 


by  the  poor  construction,  in  spite  of  the  inmates,  but  it  is 
often  at  the  sacrifice  of  comfort. 

Ventilation  by  the  Open  Fire-place. — Let  us  now  con- 
sider one  method  of  supplying  pure  air  to  a room  contain- 
ing an  open  fire  place.  A fire  must  be  kept  brightly  burn- 
ing in  the  fire-place,  to  heat  the  air  in  the  chimney  or  flue, 
causing  a difference  of  pressure  in  the  external  and  internal 
air,  so  that  the  out-door  air  rushes  in  through  every  crack 
and  crevice,  even  through  the  solid  walls,  and  thus  forces  the 
foul  air  up  the  chimney. 

It  is  found,  however,  by  experience,  that  the  openings 
mentioned  are  not  generally  sufficient  to  admit  a sufficient 
volume  of  pure  air.  Hence  our  custom  is,  at  intervals, 
when  headaches  or  debility  are  experienced,  to  open  the 
doors  or  windows  “to  let  in  a little  fresh  air.”  A wise  pre- 
caution certainly;  but  it  does  not  meet  the  whole  case,  for 
air  should  be  admitted  without  draft — i.  e.,  without  the  influx 
of  sharply  defined  cold  currents,  which,  as  is  well  known, 
produce  colds,  with  their  attendant  evils.  The  problem  has 
been  solved,  however,  in  several  ways,  the  details  of  which 
are  simple  in  the  extreme. 

Thus,  if  the  lower  sash  of  the  window  is  raised  a few 
inches  and  the  opening  below4±  is  completely  closed  by  a 
strip  of  plank,  there  will  still  remain  an  opening  between 
the  sashes  where  they  overlap,  through  which  the  air  will 
pour,  being  necessarily  directed  upwards.  It  thus  strikes 
the  ceiling,  and  is  then  gradually  diffused  through  the 
room  without  draft. 

A common  expedient  of  simply  lowering  the  top  sash  al- 
lows the  cold  air  to  “’trickle  down”  on  our  heads.  In  the 
latter  case,  however,  a board  may  be  placed  at  an  inclina- 
tion against  the  upper  part  of  the  sash,  so  as  to  give  the  en- 
tering current  an  upward  direction. 

Either  of  these  plans  is  liable  to  failure  when  curtains  or 
blinds  are  used.  So  that  a more  generally  applicable 
method  would  consist  in  boring  holes  through  the  upper 


24 


SANITARY  ENGINEERING. 


part  of  the  doors  or  walls,  and  giving  the  entering  air  an  up- 
ward direction  by  means  of  inclined  planes  of  some  kind; 
or  tubes  of  wood  or  iron  may  be  passed  through  the  walls 
and  turned  directly  upwards  on  entering.  They  should  ex- 
tend to  at  least  7 feet  above  the  floor. 

The  air  in  all  cases  should  be  drawn  directly  from  out- 
doors, and  not  from  passages  or  other  rooms.  The  open- 
ings, moreover,  should  admit  of  being  partially  or  entirely 
closed  on  very  stormy  and  windy  days.  All  of  the  above 
plans  have  been  tried  in  dwellings,  club-rooms,  etc.,  with 
complete  success. 

The  proper  size  of  tube  or  opening  to  use  must  be  deter- 
mined by  experience.  Two  tubes,  of  two  inches  diameter 
each,  may  be  tried  for  an  average- sized  room  for  two  per- 
sons. It  is  stated  that  “two  square  tubes,  5x5  inches,  will 
keep  a good-sized  club-room  fresh  ” 

Now,  this  method  of  ventilation  is  dependent  upon  a fire 
being  maintained  at  the  lower  level  of  the  room  to  cause 
the  currents  to  enter  with  sufficient  velocity.  The  system 
fails  in  summer;  when,  however,  we  do  not  object  to  the 
draft  caused  by  opening  the  doors  and  windows. 

Known  Properties  of  Air. — The  mathematics  of  this 
branch  of  the  subject,  (which  is  not  given,  as  it  seems  out 
of  place  here,)  depends  upon  certain  known  properties  of 
air  which  may  be  briefly  mentioned.  Thus  12.4  cubic  feet 
of  air  weighs  1 pound,  when  at  a temperature  of  32°  F, 
the  barometric  height  being  about  30  inches,  the  average 
pressure  at  the  sea  level. 

Since  air  is  compressible,  (its  volume  varying  inversely 
as  the  pressure,)  it  follows  that  as  we  ascend,  the  weight  of 
the  same  volume  of  air  becomes  less,  since  there  is  less  air 
above  us  than  before,  so  that  the  same  weight  of  air,  is  not 
compressed  into  so  small  a place. 

Air  likewise  expands  or  contracts  1-491  part  of  its  volume 
for  each  degree  Fahrenheit  above  or  below  the  frezing  point, 
the  pressure  remaining  the  same;  so  that  491  volumes  of 


VENTILATION. 


25 


air  at  32°  becomes  499  volumes  at  40°,  509  at  50°,  519  at 
60°,  529  at  70°,  539  at  80°,  and  549  volumes  at  90°,  whilst 
the  491  volumes  at  32°  F.  become  479  at  20°,  469  at  10°,  and 
459  at  0°  Fahrenheit. 

Again,  it  is  found  that  one  pound  of  air  can  be  raised 
1°  F.  by  the  same  amount  of  heat  that  will  raise  0.2374  lbs. 
of  water  through  one  degree,  the  air  being  subjected  to  con- 
stant pressure. 

From  such  data,  in  connection  with  the  heat  afforded  by 
different  fuels,  and  the  laws  affecting  the  flow  of  gases,  we 
are  enabled  to  compute  the  velocity  of  the  air  flowing  out 
of  the  chimney,  which  is  thus  a measure  of  the  inflow  of 
the  fresh  air.  Suffice  it  to  say  that  the  higher  the  chimney 
or  flue  the  stronger  the  draught,  as  thereby  the  difference 
of  weights  of  the  heated  air  in  the  chimney  and  a similar 
column  outside  the  chimney  is  greater. 

Ventilation  by  Gas  Jets. — In  theatres  and  closed  halls, 
a series  of  gas  jets  may  be  used  to  create  a current,  the 
heated  air  passing  outdoors  through  flues  placed  directly 
over  the  gas  jets. 

It  is  stated  that  this  plan  has  met  with  great  success  in 
two  churches  in  New  York,  the  size  of  one  of  them  (Dr. 
Scudder’s  church)  being  150x100,  of  the  other  (Dr.  Hep- 
worth’s)  125x125;  the  first  seating  2,200  and  the  second 
2,400.  There  were  14  to  20,  12  inch  round  tin  pipes,  carried 
up  in  walls  from  near  the  floor  to  and  above  the  roof.  In 
each  of  these  tubes  was  placed  three  gas  burners,  just  above 
the  registers  that  admit  air  from  the  outside.  On  simply 
heating  some  of  these  gas  jets,  the  registers  being  opened 
the  proper  amount,  there  is  caused  a quick  exhaust,  under 
complete  control,  and  an  inflow  of  pure  fresh  air.  There  is 
an  opening  in  the  centre  of  the  coiling  of  the  auditorium 
into  an  octagon  shaped  shaft  11  feet  in  diameter  in  one 
church,  16  in  the  other,  extending  above  roof,  containing 
sashes  and  outlets  to  the  outer  air.  Gas  jets  are  placed 
under  tubes  in  these  shafts  to  increase  the  current.  At 
other  parts  of  the  ceiling  are  similar  shafts,  etc.  The  nu- 


26 


SANITARY  ENGINEERING. 


merous  gas  jets  produce  such  a current  that,  in  warm  weather , 
the  entire  air  of  the  church  can  be  changed  every  five 
minutes.  The  churches  are  heated  by  hot  air  furnaces  or 
steam  coils.  (See  “ Plumber  and  Sanitary  Engineer,”  March, 
1879.) 

Ventilation  by  Fans. — Still  another  method  of  ventila- 
tion is  by  pumps  and  fans.  Most  generally,  air  is  drawn 
from  without  by  fans  located  in  the  basement,  and  is  pro- 
pelled along  ducts — over  steam  pipes  or  furnaces,  if  it  is  to 
be  heated — to  openings  into  the  various  halls  and  rooms, 
from  whence  it  escapes  by  suitable  openings,  generally 
placed  in  the  roof.  The  air  is  often  drawn  from  near  the 
ground,  but  it  is  best,  especially  in  densely  populated 
cities,  to  draw  the  fresh  air  from  a point  100  to  200 
feet  above  the  ground  down  vertical  shafts.  In  Paris,  the 
air  is  drawn  down  a shaft  180  feet  in  height,  to  supply  the 
Assembly  room.  (See  Appendix  III  for  a description  of 
the  ventilation  of  the  N.  Y.  Lunatic  Asylum.) 

Good  Effects  of  Ventilation. — It  is  evident  how  im- 
portant a factor  of  health  ventilation  is  in  crowded  school 
rooms ; in  fact  in  all  places  where  crowds  may  congregate 
and  speedly  vitiate  the  air.  The  bad  effects  are  everywhere 
admitted.  The  good  effects  of  the  systems  proposed  have 
been  proved  by  mortuary  statistics,  especially  in  school 
houses  and  hospitals.  In  a Dublin  hospital,  in  1783,  for 
25  years  when  the  ventilation  was  bad,  3,000  out  of  18,- 
000  children,  born  there,  died  within  the  first  fortnight  of 
their  birth.  With  better  ventilation  in  the  succeeding  28 
years,  550  died  out  of  every  15,072. 

The  report  of  1861  states  that  further  improvements  in 
ventilation  have  been  made,  and  deaths  from  the  “ nine-day 
fits,”  which  carried  off  most  of  the  infants,  was  then  almost 
unknown. 

The  records  concerning  ventilation  in  connection  with 
lung  diseases  is  equally  striking.  Such  diseases  thrive  in 
cities  where  the  smoke  resulting  from  the  burning  of  coal 


VENTILATION. 


27 


is  charged  with  impurities,  such  as  “hydrocarbons, sulphide 
of  ammonium,  carbonic  oxide,  and  probably  very  minute 
quantities  of  arsenic.”  Even  now  the  cry  is  going  up  from 
London  for  a purification  of  its  atmosphere  from  smoke. 
This  evil  we  do  not  suffer  much  from  in  North  Carolina, 
the  population  being  scattered  and  the  cities  small.  But 
we  need  a thorough  inspection  of  public  buildings  with  a 
view  to  proper  ventilation. 

When  it  is  known  that  30  parts  of  carbonic  acid  to  10,000 
of  air  is  often  found  in  theatres  and  public  halls,  which  is 
five  times  the  admissible  amount,  it  will  be  admitted  that 
reform  is  needed. 

Cubic  Space  Allowed. — The  amount  of  space  per  head 
allowed  in  the  room  by  various  authorities , varies  from  300  to 
1,000  cubic  feet,  the  amount  being  smaller  when  the  room 
is  only  occasionally  filled  with  its  maximum  number. 

It  is  true  that  the  air  can  be  changed  in  a small  room 
more  frequently  than  in  a large  one  to  maintain  the  proper 
degree  of  purity  or  rather  impurity,  but  the  increased 
draught  may  be  objectionable.  The  amount  of  space  act- 
ually given  per  head  in  various  school  houses  varies  from  70 
to  100  to  200  cubic  feet.  The  effect  is  that  12  parts  of  car- 
bonic acid  in  10,000  (double  the  admissible  amount)  is  com- 
mon, and  even  20  and  50  parts  are  not  unknown.  The 
effect  upon  both  teacher  and  pupils  is  of  course,  headaches, 
listlessness  and  debility. 

Lighting. — The  proper  lighting  of  school  rooms  is  as 
necessary  as  ventilation.  The  light  should  come  from  be- 
hind the  pupil  on  to  the  book  or  blackboard,  when  possible, 
and  the  windows  should  be  high,  as  most  of  the  available 
light  comes  from  above  the  level  of  our  heads.  Lighting 
directly  from  the  top  is  probably  the  most  efficient  means 
of  all  where  practicable.  The  light  should  come  mainly 
from  one  side — the  side  opposite  the  blackboards — and  the 
pupils  should  sit  with  their  backs  to  it.  The  desks  should 
be  at  such  heights  that  the  book  or  paper,  &c.,  shall  not  be 


I 


28  SANITARY  ENGINEERING. 

too  near  the  eyes,  so  that  the  tendency  to  near-sightedness 
may  be  prevented.  This  defect  is  becoming  alarmingly 
prevalent,  and  the  teacher  should  insist  upon  the  pupil 
reading  with  the  book  at  the  proper  distance  to  suit  his 
vision,  at  all  times. 

Useful  Hints. — Finally,  let  it  be  impressed  upon  all 
that  the  sense  of  smell  when  coming  from  outdoors  into  a 
room  should  warn  us  when  our  rooms  are  foul,  and  that 
doors  and  windows  should  be  opened  when  convenient,  and 
articles  of  clothing  and  bedding  should  be  aired  frequently 
to  purify  them. 

Also  let  it  be  remembered  that  even  brick  walls  can  trans- 
mit gases.  “ Pettenkofer  got  2,650  to  3,320  cubit  feet  of  air 
through  the  brick  walls  and  crannies  of  his  room,  when  the 
difference  of  temperature  inside  and  outside  was  34°  F. 
When  all  the  crannies  had  been  carefully  stopped  up,  1,000 
cubic  feet  per  hour  still  came  through  the  walls.”  There- 
fore never  allow  filth  about  any  room  or  cellar  of  the  house, 
nor  against  the  outside  walls,  for  such  filth  will  contami- 
nate the  air  that  comes  into  the  room,  and  has  been  found 
to  cause  sickness.  If  the  house  is  liable  to  such  contagion 
from  adjoining  buildings,  endeavor  to  make  it  as  air  tight 
as  possible,  after  providing  for  the  admittance  of  the  purest 
air  that  can  be  obtained  through  proper  openings.  The 
floors  of  all  houses  should  be  as  tight  as  possible. 

Heating. — Intimately  connected  with  ventilation  is  heat- 
ing; in  fact  the  two  have  generally  to  be  considered  to- 
gether. In  cold  weather  we  require  more  heat  than  our 
bodies  generate  to  make  up  for  the  loss  by  radiation  ; at  the 
same  time  we  need  fresh  air  to  breathe. 

How  admirably  are  these  two  conditions  realized  around 
a good  camp  fire,  on  a still,  cool  night ! The  active  worker 
has  just  enjoyed  his  hearty  meal,  as  only  a worker  can,  and 
with  feet  stretched  to  the  fire — that  heats  him  by  direct 
radiation — and  body  well  clad,  inspires  the  cool,  fresh  air 
of  the  country  that  invigorates  body  and  mind. 


VENTILATION. 


29 


Cool  air  to  breathe  is  as  refreshing  as  cool  water  to  drink, 
whilst  air  too  warm  may  be  compared  with  tepid  water  in 
its  effects.  This  fact  is  universally  admitted,  and  yet  it  has 
got  to  be  the  fashion,  at  the  North  especially,  to  heat  houses 
by  puffs  of  hot  air  from  furnaces  that  would  seem  more 
properly  in  keeping  with  a drying  house.  Let  us  under- 
stand clearly  the  physical  differences  in  the  various  methods 
of  heating,  and  we  can  then  form  a more  intelligent  judg- 
ment as  to  the  merits  or  demerits  of  each  particular  device. 

The  open  fire  heats  solid  bodies  in  front  of  it,  by  direct 
radiation  of  heat  rays,  which  pass  through  the  intervening 
air  with  scarcely  any  loss.  Tyndall  has  shown  that  air, 
consisting  simply  of  oxygen  and  nitrogen,  intercepts  but 
an  extremely  small  number  of  heat  rays  passing  through 
it.  The  aqueous  vapour,  found  in  all  air,  intercepts  30  to 
100  times  the  heat  that  pure  air  does.  Carbonic  acid,  per- 
fumes, etc.,  increase  the  absorption  of  heat  by  air.  The 
water  gas  in  the  atmosphere,  although  constituting  only, 
say  | per  cent,  of  it,  yet  intercepts  nearly  all  the  heat  rays 
of  the  sun  that  do  not  reach  the  earth  ; and  again  prevents 
their  too  rapid  radiation  at  night  from  the  earth.  As  Tyn- 
dall says,  “ Aqueous  vapour  is  a blanket,  more  necessary  to 
the  vegetable  life  of  England  than  clothing  is  to  man.” 
The  amount  of  heat,  however,  intercepted  by  the  air  be- 
tween the  fire  of  a room  and  solid  objects  in  front  of  it, 
although  small,  yet  does  increase  the  temperature  of  the  air 
somewhat,  though  it  is  usually  neglected  altogether.  The 
air  of  the  room  is  mainly  warmed  by  “ convection ,”  from 
coming  in  contact  with  the  solid  objects  that  have  a higher 
temperature ; the  air  next  the  solid  body  being  heated  first, 
then  rises,  to  be  replaced  by  other  air,  which  operation  is 
repeated  indefinitely,  or  until  the  whole  mass  is  heated  to 
the  same  temperature. 

There  is  thus  a continual  circulation  of  the  air  in  a room 
heated  by  an  open  fire  place,  and  generally  an  efficient 
draught  to  keep  the  air  from  being  too  much  fouled. 


30 


SANITARY  ENGINEERING. 


If  the  room  is  heated  by  steam  or  hot-water  pipes,  the 
case  is  different.  The  direct  radiation  is  small,  as  any  one 
can  test  by  trying  to  warm  his  feet  at  the  pipes  without 
actual  contact.  The  warming  is  mainly  effected,  as  in  the 
case  of  stoves  (not  over-heated)  or  hot-air  furnaces,  by  the 
air  being  warmed,  by  the  heated  pipes,  stoves  or  furnaces, 
by  convection,  and  this  air  by  its  circulation  heats  the  room 
and  its  occupants.  The  air  is  thus  warmer  than  the  furni- 
ture in  the  room ; whereas  in  heating  by  the  open  fire-place, 
the  furniture,  etc.,  is  often  warmer  than  the  air.  A person 
in  the  room  would  thus  be  continually  radiating  heat,  un- 
less the  air  was  too  warm  for  comfort.  In  addition  to  the 
objection  to  the  warm  air,  per  se,  it  has  been  previously  ex- 
plained that  heating  air  causes  it  to  become  too  dry ; so  that 
whilst  the  “ relative  humidity”  out  of  doors  may  be  80,  in 
doors  it  may  be  much  less — a disproportion  that  cannot  be 
conducive  to  health.  In  fact,  as  a writer  humorously  remarks, 
such  drying  houses  “ are  drying  the  very  flesh  off  the  bones 
of  the  Americans.” 

Still,  in  large  buildings  it  is  generally  impracticable  to 
heat  by  direct  radiation,  and  the  inmates  have  to  submit  to 
be  dried.  Again  it  is  stated  that  the  rigor  of  the  Northern 
climate  requires  that  the  air,  even  in  dwelling-houses,  be 
heated  somewhat  before  being  admitted,  If  so,  then  it  is 
still  practicable  to  heat  it  only  to  50°  or  70°  F.,  and  supple- 
ment with  the  open  fire-place. 

Summary  of  Modes  of  Keating  in  the  Order  of  Merit. 
— We  shall  conclude  this  popular  exposition  of  the  subject 
by  a condensed  summar}7  of  the  various  modes  of  heating 
in  vogue,  in  the  same  order  of  merit  as  that  given  by  Prof. 
Fleming  Jenkin,  in  “ Healthy  Houses”  (HarpeFs  Half  Hour 
Series),  a book  that  every  one  should  have. 

The  open  fire-place  is  best,  although  most  expensive,  as  it 
heats  by  radiation, , and  secures  ventilation. 

Next  follow,  in  the  order  of  descending  merit,  hot  water 
pipes,  porcelain  stoves,  hot  air  pipes,  cast  iron  stoves,  and 


VENTILATION. 


31 


last  and  worst  gas-stoves  with  no  chimney.  These  pipes 
and  stoves  heat  largely  by  convection — i.  e.,  by  heating  the 
air  next  to  them,  which  rises  and  is  diffused  through  the 
room,  the  cold  air  taking  its  place  to  be  in  turn  heated,  &c. 

Iron  stoves,  especially  when  over-heated,  emita  bau  smell, 
supposed  to  arise  from  the  charring  or  decomposition  of  or- 
ganic substances  in  the  air  by  their  contact  with  the  heated 
sides  of  the  stove  and  pipe.  Moreover,  if  the  stove  is  red 
hot,  the  poisonous  carbonic  oxide  and  other  gases  will  pass 
through  the  red  hot  iron  and  thus  enter  the  room.  The  air 
is  charred  and  dried  too  much  by  iron  stoves.  The  porce- 
lain are  far  preferable.  Hot  air  pipes  are  better,  and  more- 
over distribute  the  heat  more  uniformly;  though  if  the  fur- 
nace becomes  red  hot,  poisonous  carbonic  oxide  will  pass 
into  the  pipes.  Some  describe  the  “hot  air”  as  having  the 
“ life  taken  out  of  it.”  Hot  water  pipes  are  better  than  hot 
air  pipes;  the  air  is  not  over-heated,  and  a uniform  temper- 
ature is  preserved  for  a long  time.  It  is  much  used  in  hot- 
houses, baths,  drying-rooms,  etc. 

Exits  must  be  provided  for  the  foul  air  where  the  hot-air 
system,  the  water  pipes  or  the  gas  stoves  are  used.  For 
comfort  and  cheerfulness,  no  device  can  equal  the  open  fire- 
place, fed  with  coal,  or  oak  and  hickory  wood,  not  ignoring 
either  the  historic  pine. 

The  fresh  air  then  comes  in  through  the  walls,  tubes,  etc., 
cold , with  plenty  of  oxygen  and  perhaps  ozone  in  it,  and  is 
gradually  diffused  through  the  room  as  it  becomes  heated, 
to  give  up  the  proper  amount  of  oxygen  required  for  respi- 
ration and  combustion.  What  excuse  can  there  be  for  close 
rooms,  that  breed  debility  of  various  kinds,  when  pure,  fresh 
air  can  be  obtained  by  us  at  such  a small  cost? 


32 


SANITARY  ENGINEERING. 


CHAPTER  IV. 

WATER  SUPPLY. 

All  of  our  supplies  of  water  are  derived  from  rainfall, 
part  of  this  rainfall  evaporating  again,  part  running  off  into 
the  streams  and  thence  into  the  ocean  to  be  again  distilled 
and  sent  back  to  us  as  clouds  and  rain,  and  part  sinking 
into  the  earth  and  forming  the  small  subterranean  streams 
which  furnish  the  water  of  our  springs  and  wells.  In  run- 
ning over  or  through  the  ground,  this  water  takes  up  such 
salts  as  it  meets  that  are  soluble.  Some  of  these,  together 
with  the  air  and  carbonic  acid  dissolved,  giving  the  pleasant 
taste  to  our  usual  potable  wraters. 

Other  salts  and  gases,  derived  from  decaying  organic  mat- 
ter— dead  bodies,  manure,  filth,  etc. — are  harmful  in  the 
highest  degree,  and  have  bred  mischief  and  death  in  innu- 
merable cases. 

The  rain  as  it  leaves  the  clouds  is  pure  water  generally  ; 
but  in  falling  to  the  ground,  it  not  only  carries  with  it  me- 
chanically much  organic  matter  and  dust  that  is  floating  in 
the  air,  but  it  dissolves  various  gases,  as  oxygen,  nitrogen, 
carbonic  acid  and  ammonia  (the  usual  constituents  of  the 
atmosphere)  besides  nitric  acid  (often  formed  in  the  air  by 
the  lightning’s  flash),  and  in  the  vicinity  of  manufacturing 
towns,  the  gases  evolved  in  the  processes  used  in  the  partic- 
ular manufacture.  Water  readily  dissolves  certain  gases. 
On  simply  shaking  it  up  with  air,  the  latter  is  readily  dis- 
solved. This  principle  is  made  use  of  in  aerating  the  pure 
water,  that  has  been  distilled  from  the  salt  water  of  the  ocean, 
on  board  ships,  thus  making  it  drinkable. 

The  amount  of  oxygen,  nitrogen,  carbonic  acid  and  am- 
monia commonly  found  in  waters  is  small,  particularly  the 
ammonia;  which  last,  it  may  be  observed,  water  can  dis- 


WATER  SUPPLY. 


33 


solve  in  large  quantities.  All  of  these  gases  are  easily  ex- 
pelled by  simply  boiling  the  water. 

Rain  water  generally  contains  far  less  organic  matter  than 
river  water.  River  waters,  though,  differ  greatly  in  the 
amount  and  character  of  the  matter,  in  solution  and  sus- 
pension, as  regards  potability.  Thus,  if  water  drains  over 
an  impervious  stratum,  as  a granitic  formation,  the  water  is 
apt  to  be  soft,  and  to  contain  but  little  solid  matter  in  solu- 
tion. Some  waters  of  this  character  contain  only  from  three 
to  five  grains  of  solid  matter  to  the  gallon  ; they  possess  a 
high  solvent  power  on  lead  and  iron  pipes,  but  are  other- 
wise of  the  best  character. 

Where  the  rocks  consist  largely  of  carbonates  of  lime  or: 
magnesia,  the  waters  are  apt  to  be  hard,  their  action  on  lead 
and  iron  pipes  is  small,  and  they  require  a greater  expendi, 
ture  of  soap  in  washing,  but  are  not  otherwise  objectiona- 
ble, unless  the  carbonates  are  greatly  in  excess. 

It  is  stated  that  the  health  and  physique  of  hard  water 
districts  is  better  than  in  soft  water  districts  ; the  water  fur- 
nishing an  abundance  of  material  needed  in  the  formation 
of  the  bones. 

Each  “ degree  of  hardness”  (i.  e.,  each  grain  of  chalk  or 
sulphate  of  lime,  dissolved  in  a gallon  of  water)  will  entail, 
however,  the  additional  use  of  two-and-a-half  ounces  of 
soap  for  every  100  gallons  of  water;  so  that  it  is  well  to  get 
rid  of  the  carbonates  in  solution,  if  possible.  This  may  be 
partially  effected  in  two  ways;  either  by  boiling  the  water, 
or  by  adding  milk  of  lime.  Both  methods  depend  on  the 
fact  that  water  can  dissolve  only  two  grains  per  gallon  of 
carbonate  of  lime,  unless  it  contains  carbonic  acid  in  solu- 
tion, when  it  can  dissolve  very  much  more. 

Boiling  expels  this  acid  ; thus  reducing  the  amount  of 
carbonate  of  lime  in  the  water  in  solution  to,  at  most,  two 
grains  per  gallon.  By  the  second,  called  “ Clarke’s  process,” 
the  added  lime-water  combines  chemically  with  all  the  free 
carbonic  acid,  forming  carbonate  of  lime,  which  thus  settles 
3 


34 


SANITARY  ENGINEERING, 


to  the  bottom,  together  with  much  of  the  original  carbonate 
of  lime,  leaving  only  about  two  grains  per  gallon  still  in 
solution  of  carbonate  of  lime. 

The  milk  of  lime  is  made  by  shaking  up  a small  quan- 
tity of  quick  lime  in  water. 

Permanent  hardness  of  water  is  caused  by  the  presence 
of  sulphates  of  lime  and  magnesia.  Neither  boiling  nor 
Clarke’s  process  can  soften  such  water. 

Wells  and  Springs. — Where  wells  or  springs  are  used  as 
the  source  of  water  supply,  great  care  should  be  taken  that 
the  surface  in  their  vicinity  be  kept  free  from  organic  mat- 
ter, which  by  oxidation  and  putrefaction  readily  forms  solu- 
ble nitrates,  ammonia  and  chlorides. 

Such  waters  are  often  clear , pleasant  to  the  taste , sparkling  from 
/the  excess  of  carbonic  acid  and  cool  from  the  effects  of  the  nitrates. 
Hence  the  senses  cannot  be  relied  on,  without  the  aid  of  a 
• chemical  and  microscopical  analysis  to  decide  whether  our 
well  water  is  fit  to  drink.  Even  when  all  filth,  slops,  etc., 
are  removed  to  a distance,  we  can  only  infer  that  there  is 
no  probable  contamination. 

The  geological  structure — stratification,  faults,  character 
of  the  earth,  etc. — should  be  studied  in  this  connection. 
Thus  it  was  found  in  a certain  locality  that  wrells  very  near 
a grave  yard  gave  good  water,  whereas  wells  on  the  oppo- 
site side,  several  hundred  yards  off,  in  the  direction  of  the 
dip  of  the  strata,  were  polluted  to  a dangerous  extent.  The 
explanation  is  simply  that  water  has  a tendency  to  flow 
along  the  planes  of  stratification,  where  the  strata  are  well 
defined. 

Numerous  cases  of  fever,  cholera,  &c.,  have  been  traced 
to  bad  water;  localities  with  wells  situated  on  the  subter- 
ranean current  that  flowed  past  the  diseased  refuse,  cess 
pool,  etc.,  being  attacked,  whilst  neighboring  localities  were 
free  from  the  epidemic.  It  is  needless  to  specify  particular 
instances.  Let  no  wells  be  placed  where  kitchen  refuse, 
slops,  manure  or  any  kind  of  fecal  matter  can  drain  into 


WATER  SUPPLY. 


35 


them.  Where  no  stratification  exists,  then,  if  possible, 
place  the  well  two  or  three  times  its  depth  from  any  offend- 
ing matter.  A well  can  just  as  properly  be  dug  next  to  the 
house  as  elsewhere,  provided  slops  and  kitchen  refuse  are 
emptied  some  distance  from  it.  In  one  instance  soapy  water 
was  found  by  analysis  in  one  well,  whose  sparkling  waters 
would  never  have  suggested  it.  The  whole  of  the  slops  of 
the  establishment  were  thrown  where  they  drained  directly 
into  the  well. 

It  must  be  carefully  borne  in  mind  that  the  well  is  the 
point  of  least  resistance  to  the  numerous  little  streams  en- 
tering it  and  that  it  may  induce  a flow  from  a considerable 
extent  of  the  surrounding  earth.  Chemical  analysis  can 
alone  show  if  some  of  these  little  streams  have  been  pol- 
luted ; in  fact,  whether  a well  is  the  drainage  receptacle  of 
the  filth  on  the  surface  or  of  the  rotten  cess  pool — the  dis- 
grace of  any  land  where  it  is  found. 

It  is  not  intended  to  convey  the  idea  that,  before  wells 
are  dug,  the  underground  water  is  necessarily  flowing  in 
little  streams.  On  the  contrary  it  is  generally  otherwise, 
particularly  in  very  absorptive  strata.  Very  hard  rocks,  of 
course,  hold  but  little  water,  except  in  the  crevices,  whilst 
very  porous  and  absorptive  strata,  as  the  London  chalk,  are 
fully  saturated  with  water  from  near  the  surface  downwards 
and  only  need  tapping  to  afford  it  in  large  quantities. 

The  water  thus  contained  in  the  ground  is  known  as  the 
“ soil”  or  “ground”  water.  Where  the  earth  is  porous, 
absorptive  and  uniform  in  character,  much  more  of  the 
rain  water  passes  into  the  ground  to  flow  off  along  subter- 
ranean channels  to  some  outlet,  to  appear  at  the  surface 
again  as  springs,  or  to  be  pumped  out  of  wells — than  where 
the  surface  is  more  impervious. 

The  imaginary  line  connecting  the  water  level  of  springs 
and  wells  (when  not  used)  is  called  “ the  line  of  saturation.” 
It  has  been  found  that  in  uniform  earth  this  line  of  satura- 
tion generally  rises  with  the  ground,  so  that  generally  as 


80 


SANITARY  ENGINEERING. 


we  recede  from  the  sea-coast,  or  a stream,  the  water  level  of 
the  well  rises,  whilst  its  depth  beneath  the  surface  increases. 
This  rule  is  often  true  even  when  there  is  a want  of  uni- 
formity in  the  strata  or  in  the  configuration  of  the  ground,, 
though  so  much  depends  upon  the  inclination  the  beds 
have,  and  their  relative  permeability,  that  it  is  impossible 
to  lay  down  any  precise  rules  as  to  w'here  water  may  be 
struck  in  any  but  the  simplest  cases. 

This  is  still  more  evident  if  the  rocks  are  contorted,  fis- 
sured or  faulted. 

Some  special  cases  may  be  given  however.  Thus  if  a 
porous  stratum  overlies  an  impervious  one,  the  water  de- 
scends through  the  former  until  it  reaches  the  latter.  Now 
as  the  lower  stratum  is  level,  or  slopes  towards  its  outcrops, 
or  is  depressed  in  the  middle,  the  water  which  soaks  through 
the  porous  stratum  will  eventually  appear  in  the  form  of 
springs  near  the  upper  line  of  the  outcrop  of  the  lower 
stratum,  or  be  mostly  stored  in  the  depression  mentioned  of 
this  stratum.  Unless  the  porous  stratum  is  very  shallow,, 
wells  may  be  dug  in  it,  especially  in  the  last  case  mentioned, 
with  the  expectation  of  getting  a good  supply  of  water. 

Where  the  porous  stratum  is  covered  ^by  an  impervious 
one,  it  holds  less  water  than  in  the  previous  case,  for  it  now 
receives  no  water  except  along  its  outcrop. 

Where  such  porous  strata,  however,  are  of  great  extent 
and  have  a considerable  outcrop  (it  may  be  in  remote  dis- 
tricts) a good  supply  of  water  may  be  expected. 

In  the  latter  case,  if  the  porous  stratum  is  again  underlaid 
with  an  impervious  one  which  is  depressed  in  the  middle, 
large  quantities  of  water  will  collect  in  this  basin  under 
considerable  hydrostatatic  pressure.  If  this  pressure  is 
sufficient  to  send  wrater  to  the  surface  through  a well  holer 
the  result  is  an  artesian  well,  which  wrells  are  much  re- 
sorted to  in  some  countries. 

In  this  State  we  need  have  no  fears  of  a water  famine  if  the 
various  sources  are  utilized.-  In  the  Quarternary  sand  of 


WATER  SUPPLY. 


37 


the  eastern  portion  of  the  State,  wells  only  15  feet  deep  are 
eoinmon,  though  the  underlying  Tertiary  marls  and  older 
rocks  may  cause  exceptional  features.  In  the  middle  and 
western  portion  of  the  State,  the  rocks  are  sandstones,  slates 
and  various  crystalline  rocks,  which  are  often  fissured, 
faulted,  contorted  or  intersected  by  trap  dykes;  thus  caus- 
ing abnormal  features : still,  as  the  dip  except  in  the  sand- 
stone formation  is  often  considerable,  there  is  not  generally 
much  difficulty  in  finding  water  on  digging  for  it;  so  that 
the  “ diviner”  with  his  witch  hazel  twig  generally  finds  his 
predictions  verified.  Perhaps  it  would  be  the  same  if  he 
did  not  invoke  its  mysterious  powers  to  assist  him  ! In  the 
older  rocks,  the  water  often  collects  in  fissures.  Instances 
are  known  where  pumping  from  one  well  affects  a remote 
one  ; whilst,  on  the  other  hand,  owing  to  faults,  dykes, 
change  of  dip,  etc.,  wells  very  near  together  seem  to  have 
no  connection. 

As  a rule,  the  wells  are  deeper  in  the  older  rocks;  for,  as 
the  latter  are  more  impervious  than  the  sands  of  the  later 
formations,  less  water  is  absorbed  by  them — more  running 
off  into  the  streams — therefore  we.  should  naturally  expect 
to  go  deeper  for  a constant  supply.  Other  things  being 
equal,  the  deeper  the  well  the  purer  the  water,  as  it  has 
filtered  through  a greater  extent  of  earth. 

The  earth  is  thus  a vast  sponge,  ready  to  afford  water 
when  tapped,  that  is  generally  of  a better  quality  too  than 
lake  or  river  water  in  the  vicinity. 

Prof.  Nichols  (see  “ Filtration  of  Potable  Waters,”)  has 
observed,  that  even  when  the  well  is  situated  near  a stream, 
that  “ the  water  is  generally  clear  and  colorless,  of  a nearly 
uniform  temperature,  and  differs  in  chemical  character  from 
that  of  neighboring  streams  or  ponds,  generally  being  some- 
what harder.” 

On  lowering  the  level  of  the  water  in  such  basins  by 
pumping  or  otherwise,  the  ground  water  level  is  lowered 
next  the  basin  to  the  same  extent ; but  it  is  found  that  as 


38 


SANITARY  ENGINEERING. 


we  proceed  from  the  well  or  basin,  that  this  level  is  lowered 
less  and  less,  until  we  reach  a point  which  is  not  affected 
when  the  level  of  the  water  in  the  basin  is  kept  at  a certain 
minimum  height,  the  friction  and  capillarity  balancing 
gravity  here ; supposing  always  the  rain  fall  not  subject 
to  much  variation.  In  case  of  drought,  of  course  the  whole 
ground  water  level  would  be  lowered. 

As  an  illustration  of  the  above  principle,  it  was  found  on 
the  Elbe,  that  when  the  water  in  a well,  dug  in  an  alluvial 
deposit,  was  kept  constanly  8.2  feet  below  its  normal  level, 
that  the  height  of  the  ground-water  was  affected  in  every 
direction  for  200  feet  only. 

Large  basins,  near  streams,  are  often  used  as  the  source 
of  water  supply  of  whole  towns.  Now  it  is  evident  that  if 
the  water  level  is  lowered  in  such  a basin  that  since  the 
water  level  in  the  intervening  bank  is  lowered,  that  the 
river  water  will  have  a tendency  to  flow  towards  the  well 
to  make  up  the  deficiency,  unless  the  bottom  and  sides  of 
the  river  have  become  coated  with  clay  to  such  an  extent  as 
to  be  impervious,  which  is  very  apt  to  be  the  case  unless  the 
stream  is  very  clear,  or  has  a rapid  current.  Known  ex- 
amples seem  to  show  little  or  no  contamination  from  the 
river  water  when  the  basins  are  built  100  to  200  feet  from 
the  river.  The  basin  is  constructed  next  a stream,  as  there 
is  apt  to  be  a greater  flow  of  ground  water  there ; besides 
the  water  in  the  stream  can  make  up  any  deficiency  by  use 
of  proper  constructions. 

Filtration. — This  natural  filtration  of  water  through  the 
soil,  when  the  latter  is  good,  is  more  efficient  than  any  sys- 
tem of  artificial  filtration,  which,  when  practiced  on  a 
large  scale,  generally  consists  in  passing  water  through 
layers  of  sand  and  gravel  about  six  feet  deep.  The  finest 
sand  is  put  at  the  top,  the  upper  portion  of  which  catches 
most  of  the  suspended  matters,  and  by  the  oxygen  con- 
densed in  its  pores,  frees  the  water  of  a small  portion  of  its 
organic  matter. 


WATER  SUPPLY. 


39 


As  the  sand  becomes  clogged,  it  is  scraped  off  at  top  and 
fresh  sand  added. 

It  is  well  not  to  cause  the  water  to  flow  through  the  filter 
at  a rate  greater  than  fifty  gallons  per  square  foot  of  surface 
per  day.  The  water  is  usually  several  feet  deep  on  the  filter 
bed.  The  beds  are  scraped  about  a dozen  times  a year, 
oftener  in  summer  than  in  winter. 

When  possible,  it  is  best  to  construct  settling-basins  where 
the  water  can  deposit  much  of  its  sediment  before  passing 
on  to  the  filter  beds. 

In  some  rivers,  the  particles  of  clay  in  suspension  are  so 
fine  as  to  readily  pass  through  sand  and  even  filter  paper. 
In  such  cases,  charcoal  pounded  fine  is  the  only  resource. 
The  action  of  a sand  filter  is  two  fold,  mechanical  and 
chemical: 

1st.  Mechanical,  in  that  suspended  matters  too  large  to 
pass  through  the  pores  of  the  filter  are  caught,  as  in  a net ; 
likewise  much  sediment  that  would  otherwise  pass  through 
sticks  to  the  grains  of  sand,  due  to  the  property  of  adhesion. 

2nd.  Chemical,  for  although  sand  filters  have  practically 
no  action  on  dissolved  mineral  matter,  yet  an  appreciable 
quantity  of  organic  matter  in  solution,  particularly  certain 
kinds,  are  removed  by  filtration  through  them. 

An  experiment  that  any  one  can  perform  will  illustrate 
this : Add  a few  drops  of  sulphate  of  indigo  solution  to  some 
clear  water  ; the  water  assumes  an  intense  blue  color,  vhich 
color  it  retains  on  filtering  through  an  ordinary  filtering- 
paper.  But  if  we  strew  over  the  filter  paper  some  powdered 
charcoal  (animal  charcoal  is  best)  the  water  comes  through 
perfectly  colorless.  If  we  use  earth  in  place  of  the  charcoal, 
the  water  that  passes  through  it  is  slightly  colored,  thus 
showing  that  earth  is  not  so  powerful  an  agent  as  charcoal. 
Now,  evidently,  here  the  earth  or  the  charcoal  have  exer- 
cised a different  influence  from  the  filter  paper  alone.  The 
filter  paper  will  catch  suspended  matter.  Thus  muddy  water 
passed  through  it  may  become  clear,  but  it  does  not  alter 


40 


SANITARY  ENGINEERING. 


chemically  the  substance  in  solution.  We  have  just  seen, 
though,  that  earth  or  charcoal  does,  and  the  usual  hypothe- 
sis to  account  for  this  fact  is  that  “ porous  substances  con- 
dense gases — air,  oxygen,  etc.,  in  proportion  to  the  extent  of 
their  interior  surface,”  and  this  oxygen  actually  destroys  by 
slow  combustion  the  substance  in  question.  The  enormous 
amount  of  surface  to  volume  of  porous  charcoal  or  piles  of 
earth  permits  the  condensation  of  a large  amount  of  gas 
which  stands  ready  to  attack  any  chemical  body  that  can  be 
decomposed  or  altered  by  it. 

Of  course  this  chemical  action  must  diminish  the  more 
the  longer  the  filter  is  in  action,  as  the  oxygen  is  not  so 
readily  replaced  when  the  filter  is  covered  with  water.  If 
water  is  really  polluted  by  sewage  matters,  it  has  been  shown 
that  it  may  be  improved  materially  but  not  perfectly  puri- 
fied by  filtration.  It  is,  therefore,  pertinent  to  ask,  what 
amount  and  kinds  of  organic  matter  found  in  water  render 
it  unfit  for  drinking? 

Evidently,  we  must  consider  the  two  questions  together. 
Organic  matter,  per  se,  cannot  always  be  deleterious,  other- 
wise soup  would  have  to  be  ranked  as  poison.  It  is  stated 
that  the  waters  of  the  Dismal  Swamp,  saturated  with  or- 
ganic matter,  is  actually  preferred  by  sea-going  vessels  to 
purer  waters.  Chemistry  is  perfectly  able  to  determine  the 
mineral  salts  dissolved  in  water,  and  medicine  can  pro- 
nounce upon  the  amounts  that  may  be  taken  into  the  sys- 
tem without  injury.  Chemistry  can  likewise  determine  the 
amounts  and  kinds  of  organic  matter  in  any  water,  and  if 
the  source  is  known  to  be  bad,  or  the  organic  matter  (espe- 
cially the  albuminoids)  in  excess  over  good  potable  waters 
in  the  vicinity,  the  chemist  is  able  to  form  an  intelligent 
opinion,  at  least  as  to  the  “possible  amount  of  germ”  or 
disease  producing  power  of  the  water. 

London  drinks  Thames  water  principally,  though  “above 
the  point  where  the  supply  is  abstracted  the  river  is  contami- 
nated by  the  excrements  of  more  than  200,000  human  beings.” 


WATER  SUPPLY. 


41 


Those  who  favor  this  water,  claim  that  a polluted  river 
purifies  itself  in  its  onward  flow,  the  noxious  matter  being 
oxidized  as  it  is  tossed  to  and  fro  by  the  current  and  thus 
rendered  innocuous,  besides  being  more  and  more  diluted. 
Again,  fish  eat  fresh  fecal  matter,  and  vegetation  can  ab- 
stract large  quantities  of  it.  Still,  it  is  doubtful  if  this  nat- 
ural process  is  continued  long  enough  to  thoroughly  destroy 
the  hurtful  part  of  the  sewage. 

Now  can  this  Thames  water  be  regarded  as  a fit  source 
for  water  supply,  having  once  been  contaminated  to  a cer- 
tain extent?  “ The  noxious  part  of  sewage  is  that  which  is 
held  in  mechanical  suspension,  and  these  globules  are  be- 
yond the  reach  of  the  chemist,  and,  to  a great  extent,  of  the 
microscopist.  There  are  only  two  processes  by  which  it  can 
be  effectually  removed;  the  one  is  boiling  for  a long  time, 
and  the  other  is  by  distillation,  both  impracticable  on  a 
large  scale.”  “ No  process  of  filtration  that  has  yet  been 
devised  will  remove  choleraic  dejections  from  water.”  (Hum- 
ber’s Water  Supply,  p.  19.) 

The  organic  matter  is  not  then  considered  as  fatal  in 
itself,  but  as  dangerous,  when  of  certain  kinds,  as  affording 
a refuge  and  breeding  ground  for  the  poison  germs  that 
attend  an  epidemic.  A person  may  drink  even  diluted 
sewage  with  but  slight  inconvenience  until  this  germ  is 
once  planted  in  it,  when  at  once  his  beverage  changes  to  a 
rank  poison. 

Whether  we  accept  the  germ  theory  or  not,  it  is  admitted 
that  drinking  foul  water  and  breathing  impure  air  debili- 
tate the  system  and  thus  render  it  less  able  to  withstand 
epidemics.  Let  us  then  follow  the  natural  instincts  and 
avoid  polluted  air  and  water,  especially  as  North  Carolina 
can  afford  the  pure  articles  in  such  abundance. 

Lead  Poisoning. — There  is  one  source  of  poisoning  that 
may  be  considered  by  itself — lead  poisoning , due  to  the  use 
of  lead  cisterns  and  lead  pipes. 


42 


SANITARY  ENGINEERING. 


Soft  waters  that  contain  oxygen  oxidize  the  lead  and  then 
dissolve  the  lead  oxide  formed.  Hard  waters,  containing 
free  carbonic  acid,  form,  on  the  contrary,  carbonate  of  lead, 
which  is  only  soluble  to  the  extent  of  one  part  in  seven 
thousand,  unless  there  is  much  free  carbonic  acid  present. 
Clarke’s  softening  process  lessens  the  action  of  water  on  lead. 
Peat}'  matters  form  a sort  of  protecting  coating  on  the  lead 
pipe  that  is  very  efficacious  in  preventing  further  action  on 
the  lead.  One-tenth  of  a grain  of  lead  per  gallon  of  water 
may  produce  lead  poisoning  in  time. 

The  presence  of  lead  in  water  is  easily  detected  by  passing 
a current  of  sulphuretted  hydrogen  through  a deep  column 
of  the  acidified  water.  If  the  liquid  becomes  tinged  of  a 
brown  color,  it  is  due  to  the  formation  of  lead  sulphide. 
What  is  the  remedy  if  the  water  is  found  to  act  continuously 
on  the  lead  ? Simply  abolish  the  lead  cisterns  for  slate,  or 
stone  ware,  or  galvanized  iron  cisterns,  and  replace  the  lead 
pipes  by  wrought  iron  pipes  with  screw  joints.  The  tin 
lined  lead  pipe  has  not  proved  satisfactory ; a small  flaw 
exposes  the  lead,  a galvanic  action  between  the  two  metals 
is  commenced  and  the  water  is  speedily  poisoned. 

It  is  of  the  greatest  importance  to  observe  that  no  cistern 
or  water  pipes  should  be  placed  where  sewer  gases  may  pass 
either  through  or  over  them,  in  contact  with  the  water,  since 
water  is  very  absorbent  of  such  gases. 

Cistern  Water. — Where  rain  water  is  used  as  the  source 
of  supply,  it  is  collected  from  the  house  roofs  and  stored  in 
cisterns  of  wood  or  brick  in  cement.  The  cistern,  if  of  wood, 
should  have  a circular  form ; if  of  brick,  any  convenient 
form  can  be  used,  provided  the  earth  is  well  rammed  behind 
the  walls,  to  enable  the  latter  to  withstand  the  outward  pres- 
sure of  the  water.  The  cistern  should  be  covered  and  ven- 
tilated. 

The  rain  water  as  it  descends  brings  down  many  impu- 
rities from  the  atmosphere,  such  as  soot,  acid  fumes,  oil,  etc., 
particularly  in  the  manufacturing  centres;  besides  if  or- 


WATER  SUPPLY. 


43 


ganic  impurities  in  the  shape  of  dust,  such  as  horse  ma- 
nure, etc.,  cover  the  roof,  the  water  is  further  contaminated 
before  it  reaches  the  cistern.  The  character  of  the  roof  like- 
wise, whether  lead  painted,  formed  of  new  shingles  or  de- 
cayed ones,  etc.,  must  be  considered.  We  thus  see  that  cis- 
tern water  is  not  necessarily  perfect,  though  it  is  probably 
better  than  well  waters,  for  while  it  has  not  had  the  benefit 
of  the  natural  filtration  of  the  latter,  still  it  has  taken  up  no 
new  salts  from  the  ground,  and  has  certainly  escaped  sew- 
age contamination. 

Nevertheless,  it  should  be  filtered  before  being  used.  This 
is  effected  in  various  ways.  One  plan,  when  the  brick  cis- 
tern is  used,  is  to  divide  the  cistern  by  a porous  wall  into 
two  unequal  parts.  The  foul  water,  let  into  the  larger  divi- 
sion, filters  through  the  porous  wall  into  the  smaller  divi- 
sion, from  whence  it  is  pumped  over  the  house.  The  po- 
rous wall  may  be  made  of  soft  bricks,  or  of  some  filtering 
material,  as  porous  tiles  or  blocks  of  animal  (bone)  charcoal, 
that  may  be  placed  in  a frame  which  can  slide  in  groves 
and  be  readily  replaced  when  the  filter  has  become  clogged 
up. 

The  brick  wall,  although  very  efficient  at  first,  becomes 
clogged  up  in  a few  months  by  solid  matter,  consisting, 
amongst  other  things,  of  insects,  worms,  etc.;  so  that  the  fil- 
tration then  is  rather  an  injury  than  a benefit,  as  chemical 
analysis  has  demonstrated.  The  solid  matters  that  settle  at 
the  bottom  of  cisterns  should,  of  course,  be  removed  when- 
ever practicable. 

Domestic  Filters. — With  regard  to  domestic  filters  of 
any  kind  whatsoever,  it  may  be  observed  that  the  filtering 
material  requires  renewal  every  few  months. 

The  following  is  an  extract  from  the  “Sixth  Report  of  the 
River  Pollution  Commissioners  of  England 

“ It  cannot  be  too  widely  known  that,  as  a rule,  domestic 
filters  constructed  with  sand,  or  sand  and  wood  charcoal, 


44 


SANITARY  ENGINEERING. 


are  nearly  useless  after  the  lapse  of  four  months,  and  posi- 
tively deleterious  after  the  lapse  of  a year.” 

“ Of  all  material  for  domestic  filtration,  with  which  we 
have  experimented,  we  find  animal  (bone)  charcoal  and 
spongy  iron  to  be  the  most  effective  in  the  removal  of  or- 
ganic matter  from  water.” 

“ Tiie  removal  of  mineral  constituents,  and  the  consequent 
softening  of  the  water,  ceases  in  about  a fortnight,  but  the 
withdrawal  of  organic  matter  still  continues,  though  to  a 
greatly  diminished  extent,  when  the  filter  is  much  used, 
even  after  the  lapse  of  six  months.” 

“We  found  that  myriads  of  minute  worms  were  develop- 
ed in  the  animal  charcoal,  and  passed  out  with  the  water 
when  the  filters  were  used  for  Thames  water,  and  when  the 
charcoal  was  not  renewed  at  sufficiently  short  intervals,  a 
serious  drawback  to  its  use.” 

The  spongy  iron  is  free  from  this  trouble,  but  the  filtered 
water,  especially  the  first  portions  filtered,  contain  iron  ; and 
the  softer  the  water  the  more  iron  dissolved. 

On  the  whole,  it  would  seem  that  for  hard  waters  “Bis- 
chop’s  Spongy  Iron  Filter”  is  best,  though  the  animal  char- 
coal is  an  admirable  material,  when  renewed  every  few 
months.  Chemical  analysis  can  alone  tell  when  the  filter 
has  ceased  action. 

Both  materials  (spongy  iron  and  animal  charcoal,)  remove 
about  the  same  quantity  of  “albuminoid  ammonia,”  say  one 
fourth,  as  a mean  of  some  very  careful  experiments,  (Nichols 
on  Filtration  of  Potable  Water),  this  substance  being  taken 
as  the  measure  of  the  suspicious  organic  matter  in  solution 

From  an  analysis  by  Bischof  (Humber’s  Water  Supply) 
it  would  seem  that  the  spongy  iron  (a  metallic  iron  reduced 
from  an  oxide  without  fusion,  and  hence  in  a loose  spongy 
state)  was  a more  efficient  agent  than  “magnetic  carbide” 
and  “silicated  carbon,”  two  other  materials  that  have  been 
used  with  success. 

If  animal  charcoal  is  used,  it  should  be  in  lumps  in  pref- 


WATER  SUPPLY. 


45 


erence  to  blocks,  though  the  latter  gives  good  results.  An 
admirable  filter,  that  may  be  used  in  any  cistern,  consists 
of  a metallic  vessel  with  a perforated  bottom,  filled  with  an- 
imal charcoal  and  having  a pipe  leading  from  the  top,  which 
must  be  below  the  level  of  the  water  in  the  cistern.  The 
water  of  the  cistern  passes  up  through  the  perforated  bot- 
tom, then  filters  through  the  charcoal  and  is  drawn  off 
by  the  pipe  when  it  is  needed.  The  advantage  of  this  ar- 
rangement is  this:  the  suspended  particles  are  caught  most- 
ly at  the  bottom  of  the  filter  and  may  become  detached  from 
the  filter,  especially  if  water  is  forced  through  it  from  the 
top  in  a downward  direction  at  intervals.  The  filter  can  of 
course  be  taken  out  at  any  time  and  the  material  se rated  or 
renewed.  Many  other  materials  have  been  used  for  filters 
of  small  size — sponge,  sand,  cotton,  flannel,  earthenware, 
common  charcoal,  etc.  The  small  size  filter  acts  simply  as 
a strainer  in  a short  time,  and  requires  frequent  renewing, 
otherwise  it  is  worse  than  useless.  Makers  of  all  kinds  of 
filters,  however,  do  not  hesitate  to  aver  that  they  are  self- 
cleansing, perfect,  etc.,  etc.,  which,  we  have  seen,  is  opposed 
to  the  best  and  latest  scientific  research  on  the  subject.  Let 
the  householder  be  guided  by  the  facts. 

Where  nothing  better  is  at  hand,  water  may  be  filtered 
through  a box  perforated  at  the  bottom,  containing  clean 
quartz  sand,  resting  on  a plate  of  porous  earthenware  or  on 
bricks  placed  on  top  of  the  charcoal.  Expose  the  filter  to 
the  air  from  time  to  time. 

Public  Systems  of  Water  Supply.— It  will  probably 
not  be  long  before  our  cities  will  demand  purer  water  than 
can  be  supplied  by  the  wells  and  springs  now  used ; many 
of  them  being,  without  doubt,  polluted  by  the  many  impu- 
rities thrown  on  the  surface.  This  involves  a public  system 
of  water  supply,  with  its  attendant  system  of  reservoirs,  fil- 
ter beds,  pipes,  hydrants,  etc.  In  view  of  such  contingency, 
it  may  not  be  out  of  place  to  mention  some  of  the  require- 
ments that  such  a system  should  fulfill. 


46 


SANITARY  ENGINEERING. 


The  water  may  be  obtained  from  lakes,  rivers  and  streams, 
springs  and  wells,  impounding  reservoirs  often  being  used 
to  collect  that  which  falls  on  the  hill  sides  into  one  place. 

This  water  may  be  conveyed  for  distribution  (Rawlin- 
son’s  Suggestions  to  Local  Sanitary  Boards,  England,  p 20,)— 

“ By  means  of  open  conduits  (before  filtration) ; 

“ “ covered*  “ (always  after  filtration) ; 

“ “ cast  iron  pipes  under  pressure. 

A water  supply  may  be  gravitating,  or  the  water  may  be 
pumped  by  steam  power.  The  relative  economy  of  one  or 
the  other  form  of  works  will  depend  on  details  of  cost  and 
quality  of  water;  as  a rule,  gravitating  works  require  the 
largest  capital.  The  annual  working  expenses  of  a pump- 
ing scheme  may,  however,  be  greatest.  Reservoirs  for  ser- 
vice distribution  should  be  covered. 

If  filters  are  used,  the  water  should  not  be  exposed  in 
open  reservoirs  and  tanks  after  filtration. 

Cast  iron  pipes,  properly  varnished,  should  be  used  for 
street  mains.  Lead  should  not  be  used  with  soft  water, 
either  in  service  pipes  or  in  cisterns.  Wrought  iron  tubes 
with  screw  joints  may  be  used  for  home  service. 

Water  at  and  below  six  degrees  of  hardness  is  considered 
soft  water;  above  this  range,  water  is  termed  “ hard.” 

These  “ suggestions  ” of  Mr.  Rawlinson,  (Chief  Engineer- 
ing Inspector  to  the  local  government  board,  London,)  are 
valuable,  especially  as  they  represent  the  best  modern  thought 
on  this  subject,  and  may  tend  to  prevent  fatal  mistakes  in 
designing  water. supply  systems. 

As  he  says,  “ The  great  modern  improvement  in  water 
supply  is  the  delivery  by  constant  service , and  at  high  pressure, 
over  the  entire  area  of  a town,  and  into  every  house,  cot- 
tage and  tenement,  and  should  be  secured  where  practi- 
cable.” 

The  “ constant  supply  at  high  pressure  ” permits  con- 


♦Covered,  to  prevent  the  growth  of  vegetable  organisms. 


WATER  SUPPLY. 


47 


sumers  to  draw  water  from  the  pipes  at  any  time,  and  can 
be  made  so  efficacious  in  the  extinction  of  fires  as  to  dimin- 
ish their  destructive  effects  most  materially.  Fire  engines 
are  not  needed  with  such  a system.  It  is  said  that  in  Paris, 
owing  to  the  excellent  organization  of  the  fire  department, 
that  a destructive  fire  is  almost  unknown.  The  “ intermit- 
tent supply ” does  not  offer  these  advantages.  House  cisterns 
are  required  to  stow  the  daily  allowance  of  water,  which  is 
only  supplied  at  certain  hours.  The  cisterns,  if  neglected, 
may  not  be  supplied  with  water,  or  they  may  leak,  or  absorb 
foul  gases,  and  finally  suffer  from  want  of  cleanliness. 

There  is,  besides  the  high  pressure  due  to  a sufficient  ele- 
vation of  the  reservoir  above  the  town,  the  “ Holly  System'' 
of  maintaining  this  high  pressure  in  the  pipes  by  steam 
power.  The  pumping  machinery  is  placed  near  the  water, 
which  is  pumped  directly  into  the  mains,  the  pressure  being 
kept  constant,  or  increased  or  diminished  at  will. 

This  system  is  highly  spoken  of  wherever  it  has  been 
tried. 

Source  of  Supply.  Available  Rainfall. — In  any  one 

of  these  systems,  it  is  a first  requisite  that  the  source  of  sup- 
ply shall  be  constant  and  unfailing.  Where  a large  stream 
is  used  as  the  source,  the  amount  that  can  be  depended  on 
in  the  dryest  seasons  may  be  estimated  with  some  degree  of 
certainty.  Where  small  lakes,  springs,  wells  and  small 
streams  are  used  as  the  source,  we  have  to  depend,  more  or 
less,  on  the  observed  rainfalls  for  the  different  seasons,  in 
conjunction  with  the  measured  flow  of  the  streams  if  any 
to  form,  at  best,  only  an  approximate  estimate  of  the  yield. 

Such  observations  should  be  conducted  over  a period  of 
twenty  years  if  possible,  to  include  all  fluctuations ; but  as 
a rule,  in  this  State,  we  have  only  a few  years  observations 
of  rain  fall,  and  only  one  or  two  of  the  flow’  of  streams  to  found 
an  estimate  upon  of  the  probable  yield  of  water  over  a given 
drainage  area. 

Let  us  suppose  that  an  embankment  is  thrown  across  a 


48 


SANITARY  ENGINEERING. 


valley,  to  form  a reservoir,  into  which  shall  be  stored  al 
the  water  that  drains  into  the  valley  from  its  “catchment 
ground,”  wThose  area  can  be  readily  computed,  as  it  is 
bounded  generally  by  well  defined  ridge  lines  and  the  em- 
bankment in  question.  Now  the  yearly  rain  fall  in  differ- 
ent portions  of  the  State  varies  from  20  to  60  odd  inches, 
the  average  being  high,  over  45  inches  certainly.  If  all 
of  this  could  be  collected  into  reservoirs,  the  amount  would 
be  given  by  simply  multiplying  the  catchment  area  by  the 
depth  of  the  rain  fall ; thus,  if  the  catchment  area  was  one 
square  mile,  27,878,400  square  feet,  and  the  depth  of  rain 
fall  one  foot,  we  should  have  27,878,400  cubic  feet  in  a year 
or  76,379  cubic  feet  in  one  day  for  the  supply.  But  in 
practice  we  are  very  far  from  securing  the  whole  rain  fall, 
the  reason  for  which  can  be  made  plain  by  the  following 
considerations. 

Let  us  first  suppose  the  catchment  ground  to  be  imper- 
meable and  free  from  vegetation;  then  any  rain  that  falls 
all  flows  into  the  reservoir,  except  that  lost  by  evaporation ; 
the  latter  being  less  as  the  surface  is  steeper,  the  tempera- 
ture lower  and  the  drainage  area  smaller. 

If,  however,  the  surface  of  the  ground  is  pervious,  as  is 
usual,  then  a portion  of  the  rain  fall  sinks  into  the  ground, 
to  appear  again  as  springs,  and  thus  drain  ultimately  into 
the  reservoir,  or  else  to  pass  off  by  some  subterranean 
stratum  to  other  outlets.  In  this  case  the  amount  lost  by 
evaporation  is  less  as  the  ground  is  more  absorbent  and 
better  drained,  the  slopes  steeper,  and  the  temperature  and 
area  smaller.  If  now  we  suppose  the  earth  more  or  less 
clothed  with  vegetation,  the  latter  absorbs  and  partly  evap- 
orates still  more  water.  The  conditions  of  the  problems  are 
thus  seen  to  vary  greatly  for  different  localities,  with  the 
season  of  the  year,  and  it  maybe  added,  also  with  the  winds 
and  relative  humidity  of  the  atmosphere. 

In  England,  where  observations  have  been  conducted  for 
years  over  many  distinct  catchment  basins,  the  loss  due  to 


WATER  SUPPLY. 


49 


evaporation  and  absorption,  has  been  found  to  range  from 
nine  to  nineteen  inches  per  annum,  and  it  is  the  prac- 
tice to  consider  as  available  no  more  than  the  mean 
fall  for  three  consecutive  dry  years,  (which  is  found  to 
be,  as  a rule,  J less  than  the  average  rain  fall,)  after  sub- 
tracting the  loss  by  evaporation.  Thus,  if  the  mean  fall 
for  three  consecutive  dry  years  is  about  forty  inches,, 
and  if  the  loss  by  evaporation  and  absorption  is  put  at  20 
inches,  this  would  leave  20  inches  of  rain  fall  that  could  be 
utilized  if  it  was  all  stored. 

Observations  on  Lake  Cochituate,  Mass.,  water  shed  of 
12,077  acres,  from  1852  to  1875,  gave  a yearly  rain  fall  vary- 
ing from  35  to  69  inches — average  50,  and  the  percentage  of 
this  received  into  the  lake  25  to  74 — average  about  45.  It 
is  nevertheless  recommended  by  some  good  engineers  that 
not  over  12  to  15  inches  of  rain  fall  be  counted  on  as  avail- 
ble  in  the  United  States,  which  is  less  than  Humber  allows. 

The  evaporation  from  the  surface  of  the  water  in  the 
reservoir , in  dry  seasons,  averages  about  inch  daily  in 
England,  whilst  it  is  as  much  as  | inch  in  some  localities 
in  India.  The  annual  loss  in  England  is  put  at  20  to  25 
inches.  It  is,  of  course,  much  more  in  small  and  shallow 
ponds,  which  can  be  more  readily  heated,  than  in  extensive 
reservoirs  or  lakes.  Trautwine  says  that  the  daily  loss  from 
evaporation  in  the  three  warmest  months  of  the  year  will 
rarely  exceed  inch  in  any  part  of  the  United  States.  This 
is  probably  too  high,  for  the  same  authority  found  in  the 
tropics  over  a pond  8 feet  deep,  a loss  of  only  2 inches  in 
16  days,  or  J inch  per  day.  The  thermometer  reached  115° 
to  125°  in  the  sun  every  day.  It  is  evident  from  the  fore- 
going the  importance  of  early  making  observations  in  each 
locality  for  as  long  a period  as  possible,  in  order  to  ascer- 
tain the  ratio  of  the  “ available  ” to  the  “ total  ” rainfall. 
Rankine  says  that  this  ratio  is  about  1 for  hard  rocks,  roof 
surfaces,  paved  streets,  &c.,  ^ to  ^ for  pastures,  A to  ^ for 
flat  cultivated  country,  and  0 for  chalk.  It  follows  that  a 
3 


50 


SANITARY  ENGINEERING. 


catchment  basin  is  best  located  in  the  older  formations,  con- 
sisting of  hard  rocks,  whilst  wells  suit  best  the  more  previous 
and  recent  deposits.  London  is  even  now  preparing  to  give 
up  the  Thames  water  altogether  and  to  draw  her  supply 
from  her  underlying  chalk  beds. 

It  is  important  to  note  that  the  most  reliable  method  of 
ascertaining  the  available  rainfall  is  to  measure  the  actual 
discharge  of  streams  that  drain  a given  water  shed.  Then 
by  comparison  with  the  total  rainfall  on  the  water  shed,  we 
find  the  actual  amount  lost  by  evaporation  and  absorption 
of  the  ground. 

No  town  which  contemplates  a public  water  supply 
should  neglect  to  have  such  observations  made,  covering  a 
period  as  long  as  possible,  to  take  proper  account  of 
droughts,  &c. 

Consumption  per  Head. — Statistics  show  that  in  Eng- 
land the  daily  amount  of  water  used  in  the  towns  and  cities 
varies  from  15  to  50  gallons  per  head — 30  being  regarded  as  a 
full  allowance.  In  the  United  States  the  daily  consumption 
per  head  varies  from  25  to  120  U.  S.  liquid  gallons  of  231 
cubic  inches  (1  cubic  foot — 7.48052  gallons) ; and  it  is  rec- 
ommended by  some  to  allow  40  to  50  gallons  per  head  for 
smaller  cities,  and  an  increasing  amount  as  the  population 
increases. 

It  is  very  plain,  from  the  records,  that  an  enormous  waste 
occurs  in  our  cities,  and  special  attention  is  now  being  di- 
rected to  it.  Where  inspections,  or  water  meters  have  been 
tried,  the  amount  consumed  has  often  been  reduced  to  half 
and  even  one-third  the  original  amount.  Humber  estimates 
that  20  to  25  gallons  is  a liberal  allowance.  Even  if  we 
assume  double  this,  it  still  behooves  us  to  take  every  pre- 
caution to  avoid  waste  by  the  use  of  meters  or  otherwise ; 
else  the  large  yearly  cost  of  the  water  supply  may  be  need- 
lessly doubled  or  trebled. 

Reservoir  Capacity. — Well,  assuming,  say  45  gallons^ 
the  daily  demand  on  a reservoir  is  made  up  of  the  45  gallons 


WATER  SUPPLY. 


51 


X number  of  population,  plus  the  daily  evaporation  from 
the  surface  of  the  water,  plus  any  compensation  water  to 
mill  owners  or  others.  Subtracting  from  this  the  dry 
weather  flow  of  the  streams  discharging  into  the  reservoir, 
we  get  “the  excess  of  the  demand  over  the  supply”  in  dry 
months;  and  this  multiplied  by  the  number  of  days  storage 
of  the  reservoir,  gives  its  available  capacity , or  the  volume  it 
must  contain  between  its  highest  and  lowest  working  levels. 
Some  advise  that  every  storage  reservoir  should,  if  possible, 
contain  six  months  of  the  excess  of  the  daily  demand  above 
the  daily  supply  for  the  dryest  consecutive  six  months. 
Some  English  engineers  formulate  the  following  rule,  as  the 
result  of  considerable  experience:  “The  number  of  days 
storage  of  reservoir”  equals  the  number  1,000  divided  by 
the  square  root  of  the  rainfall  in  inches  for  three  consecutive 
dry  years.  Thus,  if  this  rainfall  is  36  inches,  the  reservoir 
should  contain  1,000  + 6 = 166.7  days  storage  ; that  is,  166.7 
times  the  excess  of  the  demand  over  the  dry  weather  supply. 

The  following  table  (see  “ Engineering  News,”  Aug.  23, 
1879,)  will  show  the  great  disparity  between  the  least  and 
greatest  flow  of  streams : 


Name  of  Kiver. 

Drainage  Area 
in 

Square  miles. 

FLOW  IN  CUB  FT.  PER  SQ.  MILE. 

Greatest  Flow. 

Least  Flow. 

Connecticut, 

10,234 

20.27 

0.51 

Merrimack, 

4,136 

23.40 

0.53 

Schuylkill,  

1,800 

0.21 

Tyne,  England, 

1,100 

30.23 

Passaic, 

981 

20.33 

0.23 

Croton, 

339 

74.87 

0.15 

Concord,  

352 

12.64 

0.17 

Hackensack, 

84 

0.33 

Sudbury, 

76 

41.60 

0.05 

Croton,  W Branch,.. 

20 

54.43 

0.02 

“ These  figures  show  that  on  large  drainage  areas  the  pro- 
portional flow  is  less  in  freshets  and  greater  in  dry  seasons 
than  on  small  areas.” 


52 


SANITARY  ENGINEERING. 


The  “ least  flow  ” given  above  is  probably  the  least  flow 
on  any  day  of  the  dry  season.  If,  however,  our  reservoir  is 
to  contain,  say  6 months  supply,  then  we  desire  to  know  the 
least  average  flow  for  any  6 months  during  20  or  more  years. 
Suppose  this  to  be  0.2  cubic  feet  per  second  per  square  mile 
of  drainage  area,  or  17,280  cubic  feet  per  day  per  square  mile. 

Suppose  a population  of  10,000  consuming  daily  6 cubic 
feet  (45  gallons,  say)  per  head,  or  60,000  cubic  feet  in  all ; 
and  that  the  loss  by  evaporation  from  the  reservoir  of  10 
acres  say,  is  J inch  daily,  or  about  5,000  cubic  feet.  The 
total  daily  demand  is  thus  65,000  cubic  feet,  which  is  about 
48,000  cubic  in  excess  of  the  supply  from  the  stream ; so 
that  if  the  reservoir  is  to  contain  6 months=180  days  of  this 
excess,  its  available  capacity  must  be  48,000X180=8,640,000 
cubic  feet,  or  an  average  available  depth  over  the  10  acres  of 
20  feet. 

It  is  evident  that  if  the  daily  demand,  as  above,  is  65,000 
cubic  feet,  the  yearly  demand  thus  being  28,725,000  cubic 
feet,  that  but  little  over  10  inches  of  rainfall  over  the  1 
square  mile  of  drainage  area  has  been  secured,  since  10 
inches  on  a square  mile  gives  only  23,232,000  cubic  feet. 
This  is  certainly  within  reasonable  bounds. 

No  allowance  is  made  above  for  compensation  to  mill- 
owners. 

Of  course,  by  building  the  reservoir  of  sufficient  capacity 
the  whole  of  the  rainfall,  minus  the  loss  by  absorption,  evap- 
oration and  leakage,  can  be  utilized ; but  it  has  not  been 
found  desirable  to  build  such  huge  reservoirs  in  actual  prac- 
tice, so  that  much  of  the  rainfall  is  purposely  allowed  to  run 
off. 

Sources  of  Water  Supply  in  N.C.;  Maintenance  of 
Purity. — This  State  is  abundantly  supplied  with  unfailing- 
sources  of  water  supply  in  her  many  rivers  and  lakes,  not 
to  speak  of  the  underground  water,  which  hitherto  has  been 
the  only  source  used  in  the  supply  of  her  largest  towns. 
What  a contrast  do  the  rivers  and  streams  of  England — 


WATER  SUPPLY. 


53 


many  of  them  fouled  to  inky  blackness  by  the  refuse  of 
thousands  of  manufactories— present  to  our  own  waters, 
teeming  with  fish  and  drinkable  almost  everywhere.  It  is 
to  be  hoped  that  the  enacting  of  wise  laws  will  maintain 
their  purity,  by  forbidding  any  injurious  waste  or  crude 
sewage  from  entering  them.  If  this  system  is  inaugurated 
from  the  beginning,  much  trouble  may  be  avoided.  Eng- 
land now  is  making  a brave  effort  to  regain  the  pristine  pu- 
rity of  her  streams  ; let  us  be  careful  not  to  lose  this  thing  of 
beauty  in  our  own  waters. 

The  foregoing  notes  are  very  brief,  but  they  may  contain 
some  useful  hints  to  our  larger  towns  and  cities,  who  will 
sooner  or  later  abolish  the  polluted  well  and  adopt  a public 
system  of  water  supply. 


54 


SANITARY  ENGINEERING. 


CHAPTER  IV. 

WATER  SEWERAGE. 

Then  will  likely  follow  the  complex  system  of  water  sewer- 
age, which  is  now  regarded  as  the  best  for  the  largest  cities  ; 
though  it  is  admitted  that  it  is  a delicate  machinery  and 
requires  the  greatest  care  in  its  manipulation. 

This  system  has  been  so  thoroughly  studied  that  a suffi- 
cient literature  exists  on  the  subject  to  answer  the  needs  of 
practice ; so  that  it  is  needless  to  enter  into  any  very  tech- 
nical discussion  of  it  here. 

Conditions  that  the  system  should  fulfill. — The  object 
to  be  accomplished  by  the  system  is  to  carry  all  offensive 
matters  underground,  and  as  rapidly  as  possible , out  of  the 
city,  by  the  aid  of  the  water  used  in  the  houses  and  the  rain 
water  that  falls.  The  proper  carrying  out  of  a system  of 
this  kind  requires  the  aid  of  enlightened  sanitary  engineers 
of  experience ; above  all,  in  the  general  design.  Jenkin’s 
“ Healthy  Houses,”  already  referred  to,  is  sufficient  to  show 
the  general  reader,  not  only  the  cause  of  many  failures,  but 
the  remedy ; in  fact  some  of  the  conditions  that  the  system 
should  fulfill.  Let  it  be  borne  in  mind  by  any  town  con- 
templating the  water  system,  that  an  error  in  design,  like 
the  bad  foundation  to  a structure,  is  often  very  difficult  to 
remedy. 

Special  emphasis  is  laid  on  the  principle,  that  the  sewage 
should  be  carried  out  of  the  town  limits  quickly — say  in  24 
hours,  or  less,  when  practicable.  This  is  effected  by  a cor- 
rect adjustment  of  the  size  and  shape  of  the  sewer  to  its  fall, 
having  assumed  the  total  amount  of  sewage  that  is  to  be 
provided  for  daily.  The  question  is  one  of  hydraulics,  and 
may  be  solved  by  the  use  of  well  known  formulse  for  the 
flow  of  water  in  channels. 


WATER  SEWERAGE. 


55 


Example. — As  an  illustration,  take  the  following,  from 
“ Rawlinson’s  Suggestions  “ The  sewage  of  a town  or  vil- 
lage will  consist  of  waste  water  and  excreta  from  the  houses, 
and  the  volume,  in  round  figures,  may  range  from  100  to 
250  gallons  per  day  from  each  house.  This  volume  will 
probably  flow  off  in  about  eight  hours,  so  that  the  sewers 
must  provide  for  not  less  than  three  times  this  volume,  if 
*even  every  drop  of  roof  and  surface  water  can  be  excluded. 
As  this  cannot  in  all  cases  be  accomplished,  the  sewers  should 
provide  for  not  less  than  1,000  gallons  from  each  house ; or 
for  a town  of  1,000  houses  (5,500  population)  have  a deliver- 
ing capacity  of  about  1,000,000  gallons  (daily).  An  outlet 
sewer  of  2 feet  diameter,  laid  with  a fall  of  5 feet  per  mile, 
will  deliver  upwards  of  2,000,000  gallons,  flowing  a little 
more  than  half  full.  Lesser  diameters  will  answer  where 
there  are  greater  falls.” 

A 2 feet  sewer  thus  provides  for  doubling  the  population 
in  a few  years. 

Now  100  to  250  gallons  per  day,  from  each  house,  con- 
taining 5J  persons,  corresponds  to  from  18.2  to  45.5  gallons 
per  day  for  each  person,  which  figures  represent  about  the 
extremes  in  English  practice ; 30  gallons  being  the  usual 
allowance,  excluding  rain  water. 

In  the  case  above,  the  velocity  of  the  sewage  of  11,000  per- 
sons is  about  2 feet  per  second,  which  is  the  minimum  vel- 
ocity in  order  that  so  small  a sewer  may  be  self -cleansing . 

As  the  velocity  is  less  for  the  real  population  of  5,500, 
especially  if  they  use  less  water  than  1,000,000  gallons,  the 
inclination  of  the  sewer  should  be  increased  if  possible,  or 
“ flushing”  will  have  to  be  resorted  to,  or  the  sewer  must  be 
made  smaller  than  the  2 feet  diameter,  to  secure  the  proper 
velocity  to  make  the  sewer  self  cleansing,  and  to  prevent  the 
formation  of  the  poisonous  sewer  gases,  which  are  always 
formed  when  the  progress  of  the  sewage  out  of  the  town  is 
slow,  in  spite  of  all  the  ventilation  schemes  that  may  be 
tried. 


56 


SANITARY  ENGINEERING. 


A circular  sewer,  one  foot  in  diameter,  running  half  full, 
at  an  inclination  of  1 to  600  will  discharge  46.3  cubic  feet 
per  minute,  at  a velocity  of  118  feet  per  minute,  equivalent 
to  a discharge  of  167,000  gallons  (in  round  numbers)  in  8 
hours.  This  is  slightly  over  the  discharge  of  5,500  persons, 
allowing  30  gallons  to  each  person,  so  that  this  one  foot 
sewer  would  suffice  if  rain  water  is  to  be  disregarded. 

Amount  of  Rain  Fall  to  Pass  into  Sewers. — Let  us* 
next  ascertain  the  size  of  a sewer  on  the  supposition  that 
the  town  is  one  square  mile  in  area,  and  that  a rain  fall  of 
one  inch  in  24  hours  actually  drains  into  it.  The  rain  fall 
is  2,323,200  cubic  feet  in  24  hours  ; or  at  the  rate 
of  1,613  cubic  feet  in  one  minute.  By  use  of  proper  formu- 
lae, it  is  found  that  an  egg  shaped  sewer,  3J  by  5 feet,  run- 
ning full,  will  discharge  the  water  at  a velocity  of  3§  feet 
per  second,  the  inclination  being  taken,  as  at  first,  at  only 
5 feet  to  the  mile. 

We  can  now  readily  see,  by  this  particular  example,  how 
much  the  size,  and  hence  the  cost,  of  sewers  is  increased  by 
making  provision  to  receive  the  rain  fall.  It  is,  of  course, 
far  more  expensive  to  provide  for  the  exceptionally  heavy 
rain  falls  (as  “ 6 inches  in  2 hours,”  etc.,)  which  sometimes 
occur.  Sewerage  systems  in  this  country  do  not  provide  for 
such  exceptional  rain  falls. 

The  London  sewers  were  constructed  to  carry  J inch  rain 
fall  in  24  hours,  at  the  time  of  maximum  flow  of  sewage, 
larger  amounts  being  provided  forby  storm  water  overflows. 

It  is  found  that  different  soils,  or  surfaces,  have  not  the 
same  absorptive  power;  thus  in  London  the  sewers  in  some 
sections  deliver  one-half  the  rain  fall,  whilst  in  entirely 
paved  streets,  nearly  the  whole  of  the  water  is  drained  into 
them. 

Latham  says  that  in  Croyden,  the  soil  being  porous, 
gravel  overlying  chalk,  “the  amount  of  rain  contributed  by 
a storm  of  .72  inch  in  12  hours,  did  not  yield  more  than 
one-tenth  of  it  to  the  sewers.”  More  impervious  districts 
required  the  full  allowance  of  1 inch  in  24  hours,  togethe  r 


WATER  SEWERAGE. 


57 


with  the  sewage.  In  Dantzic,  which  is  sandy  and  flat,  \ 
inch  in  24  hours,  together  with  2 cubic  feet  of  sewage  in  8 
hours  was  assumed  as  the  basis  for  computations. 

It  is  plain  from  what  precedes,  that  any  town  contempla- 
ting a s'ewerage  system,  should  be  able  to  form  some  judg- 
ment as  to  the  amount  of  rain  water  to  be  admitted  to  the 
sewers,  if  any  at  all. 

Argument  for  and  against  excluding  rain  water 
from  sewers. — The  reasons  for  and  against  separation  of 
the  rain  water  may  be  stated  as  follows  : 

For  Separation. — It  is  urged  that  even  if  a distinct  set  of 
sewers  is  used  to  convey  away  the  rain  water,  that  it  is 
cheaper;  since  the  rain  water  sewers  can  discharge  into  the 
nearest  stream  (thus  giving  it  its  natural  volume)  and  can 
thus  be  made  shorter  than  the  sewage  conduit,  which  is 
often  carried  a considerable  distance;  besides  the  sewage 
conduit  is  very  much  smaller  and  therefore  cheaper  in  this 
case.  Again,  on  account  of  the  small  size  of  the  conduit, 
the  sewage  is  carried  out  of  town  much  more  quickly ; thus 
preventing  that  stagnation  which  sometimes  occurs  in  large 
sewers,  having  only  a thin  film  of  sewage  flowing  slowly 
over  the  bottom,  much  of  the  solid  material  being  deposited 
to  decompose  and  generate  the  most  hurtful  gases. 

Likewise,  the  manurial  value  of  the  sewage  is  increased 
and  any  expense  of  pumping  very  much  diminished. 

Against  Separation. — It  is  urged  on  the  other  side,  that 
chemical  analysis  shows  that,  in  large  cities,  the  storm  wa- 
ters wash  away  so  much  filth  as  to  render  the  water  as  im- 
pure as  the  sewage;  so  that,  at  least,  the  first  portions  of 
the  rain  fall  should  be  admitted  into  the  sewage  conduits, 
though  the  balance  may  be  passed  into  the  streams.  Also 
there  are  objections  to  the  use  of  so  many  pipes  in  the  streets; 
two  sets  of  sewage  pipes,  with  smaller  drains  often  crossing, 
besides  gas  and  water  pipes;  the  drainage  pipes  too  having 
to  be  laid  everywhere  with  a fall.  It  is  plain,  however,  that 
if  the  surplus  of  the  rain  water  is  to  be  allowed  to  go  where 


58 


SANITARY  ENGINEERING. 


it  can,  that  the  old  channels  should  at  least  be  so  much  im- 
proved as  to  prevent  flooding  of  cellars  and  formation  of 
any  stagnant  pools  anywhere.  So  much  separate  drainage 
should  at  least  be  insisted  on. 

It  is  certainly  in  the  line  of  simplicity  to  adopt  but  one 
set  of  sewers;  and  experience  shows  that  in  most  towns  it 
rarely  causes  any  inconvenience  from  flooding. 

If  drainage  pipes  have  already  been  laid,  they  should  not 
be  abolished,  even  if  sewers  are  afterwards  projected. 

Subsoil  Drainage. — If  there  is  but  one  sewer  system, 
then  the  subsoil  must  be  drained  by  small  pipes,  simply 
butted  together  at  the  ends,  so  that  the  subsoil  water  can 
enter.  The  pipes  must  be  placed  on  top  of  the  sewer  pipe  to 
prevent  any  infiltration  from  the  sewer,  which  often  hap- 
pens if  they  are  placed  below  the  sewer.  This  subsoil  drain- 
age is  especially  necessary  in  a retentive  soil,  to  render  the 
soil  porous,  so  that  it  can  more  effectually  do  its  work  of 
oxidation  on  any  gases  that  may  pass  through  the  sewer. 

The  latter  should  be  rendered  as  impervious  as  possible, 
for  leakage  through  bad  sewers  into  the  ground  soon  satu- 
rates it  with  the  vilest  poison,  that  invariably  produces  harm 
as  soon  as  it  can  find  an  outlet  to  the  outer  air. 

Form,  Inclination  and  Ventilation  of  Sewers. — Small 
circular  sewers  can  be  made  of  earthenware  pipe,  larger  ones 
of  brick  in  cement  or  of  concrete,  and  egg  shaped,  to  give  a 
greater  velocity  to  a small  flow.  Main  sewers  should  not  be 
laid  at  greater  inclinations  than  cause  a velocity  of  six  feet 
per  second,  if  possible,  to  avoid  the  cutting  out  of  the  bot- 
tom of  the  sewer  by  grit  and  other  solids.  The  location  of 
the  main  outlet  sewer  determines,  to  a great  extent,  the  po- 
sitions of  the  other  sewers,  and  should  receive  special  study. 
House  drains  should  be  trapped  and  ventilated  between  the 
house  and  sewer.  The  main  sewers  should  be  ventilated  by 
direct  communication  with  the  external  air,  at  least  every 
100  yards.  This  prevents  that  partial  and  noxious  decom- 
position which  occurs  in  close  places  having  a limited 


WATER  SEWERAGE. 


59 


amount  of  air.  “ In  fully  ventilated  sewers  the  sewer  air  is 
purer  than  that  of  some  stables,  or  even  in  a crowded  public 
room.” 

Nothing  is  so  much  insisted  on  in  the  best  modern  prac- 
tice as  thorough  and  complete  ventilation  of  all  sewers  and 
house  drains  and  pipes. 

House  Pipes. — Above  all,  in  this  water  system,  the  house 
connections  require  the  greatest  care  in  their  construction 
and  design  to  keep  the  lurking  poison  out  of  the  house ; and 
it  is  regretted  that  want  of  proper  diagrams  necessitates  the 
ignoring  of  this  branch  of  the  water  system  in  this  paper. 

Disposition  of  Sewage. — Having  briefly  considered  some 
points  of  general  interest  in  connection  with  the  design  of 
sewerage  works,  let  us  next  enquire  what  is  to  be  done  with 
the  sewage. 

The  plan  most  in  vogue  in  this  country  is  to  discharge 
the  sewage  matter  into  some  stream,  which  may  thus  be 
regarded,  in  one  sense,  as  the  continuation  of  the  sewer. 

In  the  case  of  tidal  waters,  however,  if  the  refuse  is  emptied 
near  the  city  it  floats  up  and  down  the  city  past  it,  giving 
anything  but  an  air  of  cleanliness  to  the  eye,  or  of  satisfac- 
tion to  the  nose. 

In  England,  the  law  now  “requires  that  rivers  and 
streams  are  not  to  be  polluted  by  the  admission  of  crude 
sewage,  even  from  existing  sewers.” 

Rawlinson  states  that  up  to  October,  1878,  “ there  are 
about  87  towns,  districts,  parishes,  and  places  whose  sewage 
is  disposed  of  by  irrigation.  There  are  23  towns,  &c.,  whose 
sewTage  is  disposed  of  by  precipitation , treatment  with  chemi- 
cals,, and  partial  land- filtration.  There  are  24  towns,  &c., 
whose  sewage  is  disposed  of  by  ruder  and  more  imperfect 
modes  of  filtration,  as  thiough  charcoal,  wicker  work  and 
straw.  There  are  16  towns,  &c.,  whose  sewage  is  disposed 
of  by  mechanical  subsidence  only.”  The  sewage  is  first  car- 
ried by  the  outlet  sewer  to  the  “ sewer  farm,”  where,  if  nec- 


60 


SANITARY  ENGINEERING. 


essary,  it  is  pumped  into  large  tanks,  to  be  then  treated 
according  to  some  of  the  methods  given  above. 

Irrigation  and  Filtration. — The  best  method  probably 
is  irrigation , or  filtration  through  a porous  soil. 

This  plan  might  be  carried  out  by  passing  the  sewage  at 
intervals  from  large  tanks,  where  it  is  collected,  through 
hundreds  of  earthenware  pipes,  loosely  jointed,  placed  about 
one  foot  below  the  surface  of  the  ground  and  in  parallel 
rows.  The  sewage  leaks  through  the  joints  into  the  sur- 
rounding soil,  which  purifies  it  by  absorption  and  oxidation* 
A better  known  method  consists  in  simply  passing  the  fluid 
sewage  on  to  ground,  deeply  drained.  The  purified  water 
runs  off  in  the  drains. 

By  distributing  the  sewage  over  a sufficient  extent  of  sur- 
face, it  is  found  that  the  soil  does  its  work  perfectly  ; being 
aided,  moreover,  by  the  growing  vegetation,  taking  up  much 
of  the  sewage  through  its  roots.  The  purification,  though, 
is  principally  due  to  the  earth,  which  has  the  property  of 
absorbing  and  condensing  gases,  such  as  air,  &c.;  so  that 
each  little  particle  of  earth  is  surrounded  with  condensed 
oxygen,  which  acts  upon  the  sewage  matter  the  instant  it 
comes  in  contact  with  it,  and  oxidizes  the  organic  part, — 
throwing  off  some  of  it  into  the  air — not  as  poisonous  efflu- 
via, which  is  the  result  of  decomposition  with  a limited 
amount  of  oxygen,  as  in  close  drains,  but  as  harmless 
aqueous  vapor,  carbonic  acid  and  ammonia.  The  amount 
of  oxygen  absorbed  by  the  soil  is  not  large,  but  it  seems  to 
be  replaced  as  rapidly  as  it  enters  into  combination,  and 
thus  to  furnish  an  indefinite  supply  to  the  matter  with  which 
it  combines.  (See  Johnson’s  “ How  Crops  Feed,”  pp.  218 
168,  etc.) 

It  must  then  be  distinctly  understood  that  the  putrescent 
substances  are  not  simply  absorbed  (as  usually  stated)  by  the 
earth  or  charcoal,  or  other  porous  material ; but  are  chemi- 
cally changed — oxidized  or  burnt  up — so  that  their  objec- 
tionable features  are  no  longer  perceived  ; the  nitrogen,  etc., 


WATER  SEWERAGE. 


61 


is  thrown  off  into  the  air,  or  passes  off  in  the  water  as  nitrates, 
or  nitrites,  so  that  the  earth  ultimately  has  about  the  same 
constitution  after  its  use  in  the  manner  indicated  as  before. 

At  Merthyr  the  effluent  water  from  the  filter  beds  was 
analyzed  by  Dr.  Frankland,  showing  that  when  230,  500 
and  1,200  people  were  draining  on  to  them  per  acre,  the 
effluent  water  was  respectively  30,  16  and  3 or  4 times  purer 
than  the  standard  of  fair  potable  water,  so  far  as  chemical 
analysis  is  taken  as  the  criterion. 

It  is  thus  seen  how  effectually  surface  soil,  where  there  is 
plenty  of  air,  does  its  work.  It  is  warmly  advocated  b}" 
Geo.  E.  Waring,  Jr.,  (see  “The  Sanitary  Condition  of  Dwell- 
ing Houses, ” Van  Nostrand,)  to  get  rid  of  all  liquid  refuse, 
about  the  country  or  town  house,  where  there  is  no  system 
of  sewers,  by  passing  it  through  loosely  jointed  pipes,  laid 
about  one  foot  below  the  surface  in  the  back  yard.  He 
states  that  the  system  has  been  found  to  work  admirably, 
winter  and  summer  wherever  tried. 

It  may  be  stated  that  the  efforts  that  have  hitherto  been 
made  to  utilize  the  fertilizing  properties  of  sewage  have  not 
been  profitable,  unless  in  the  way  of  irrigation.  Fine  crops 
have  been  raised  on  such  sewage  farms ; so  that  where  in- 
termittent filtration  is  adopted,  it  is  advisable  to  combine 
sewage  farming  with  it  to  lessen  the  expense. 

The  Chemical  Processes  used  so  far  have  not  been 
found  to  purify  the  sewage  thoroughly  by  themselves,  so 
that  natural  or  artificial  filtration  must  supplement  any 
chemical  treatment.  Besides  this  objection  to  the  chemical 
method,  its  cost  and  difficulty  of  manipulating  the  accumu- 
lations of  sewTage  sludge  both  make  against  it;  still  much 
of  this  sludge  must  be  removed  in  some  way  before  filtra- 
tion can  be  employed. 

In  seaboard  towns,  the  natural  outfall  for  the  sewage  is  the 
sea.  If  possible  the  sewage  should  be  carried  to  such  a dis- 
tance as  not  to  be  brought  back  to  the  town  by  wind,  tides 


62 


SANITARY  ENGINEERING. 


or  current.  The  same  remarks  apply  to  towns  situated  on 
tidal  streams  and  estuaries. 

Caution  to  our  Cities. — Most  of  our  large  towns  have  a 
clean  slate  for  sewerage  systems.  Let  not  a single  sewer  be 
built  until  a competent  engineer  plans  the  entire  system, 
otherwise  the  sewers  may  have  to  be  torn  up  eventually,  or 
the  engineer  may  be  considerably  embarrassed  in  his  designs. 
The  Secretary  of  the  Board  of  Health,  Dr.  Wood,  writes  of 
Wilmington,  that  “ there  is  an  incipient  sewer  system  here 
which  promises  to  be  a great  nuisance,  from  the  beginning 
they  have  made  with  it.”  It  seems  a pity  for  Wilmington 
to  make  a botch  of  it  the  very  first  move. 

THE  LIERNUR  SYSTEM. 

In  a paper  read  before  the  Austrian  Society  of  Engineers, 
Vienna,  (see  Baldwin  Latham’s  “Sanitary  Engineering,” 
Am.  ed.)  Mr.  J.  Chailly  says : 

“The  two  conditions  of  removal  without  producing  disa- 
greeable odors,  and  carrying  off  the  matter  in  short  periods, 
are  almost  entirely  fulfilled  in  Lieurnur’s  Pneumatic  Sewer- 
age system,  in  which  the  iron  waste-pipes,  which  are  water- 
tight and  air-tight,  are  united  to  a system  of  iron  pipes 
which  run  into  a central  station,  where  the  air-pump  is 
placed  which  pumps  all  the  matter  into  a reservoir.  The 
collection  and  sale  of  this  matter  does  not  usually  cover  the 
cost  of  the  labor.  The  reports  on  this  system  are  conflict- 
ing, and  yet  the  majority  of  them  speak  in  its  favor.” 

Mr.  C.  Norman  Bazalgette,  in  a late  paper  to  the  London 
Institution  of  Civil  Engineer,  says  of  this  S3'stem  from  the 
experience  gained  at  Leyden,  Amsterdam  and  Dodrecht, 
that  “it  was  supplementary  to,  and  not  substitutive  of,  a 
water  carriage  system,  extremely  costly,  and  its  mechanism 
was  extremely  complicated  and  liable  to  get  out  of  order. 
The  accumulation  of  sewage  residium  in  the  central  reser- 
voir, and  its  subsequent  decanting  into  barrels,  were  opera- 


WATER  SEWERAGE. 


63 


tions  which  could  not  fail  to  be  objectionable  and  offensive. 
In  conclusion,  the  system — though  it  might  have  a partial 
province  in  the  tide-locked  cities  of  the  Hague,  where  no 
system  of  sewerage  was  available — should  never  be  import- 
ed into  an  English  town.” 

It  would  seem  that  there  would  be  considerable  difficulty 
experienced  in  the  case  of  repairs  to  the  pipes  being  needed. 

THE  ROCHEDALE  PAIL  SYSTEM.* 

This  consists  simply  in  half-barrels  or  pails  being  placed 
under  the  seats  of  the  closed  privy  to  receive  the  fecal  dis- 
charges; the  pails  being  removed  about  once  a week,  after 
putting  on  a hermetically  tight  cover,  empty  disinfected 
pails  taking  their  place.  The  matter  is  carried  out  of  the 
town  at  night,  and  may  be  spread  on  old  fields,  a slight  cov- 
ering of  dry  earth  being  used  to  keep  down  the  smell,  or 
the  matter  may  be  sold  for  manure.  It  is  well  to  add  dry 
earth,  ashes  or  charcoal  every  day,  to  the  pails  in  use,  and 
moreover  to  ventilate  the  privy. 

This  system  is  an  excellent  one  for  most  of  our  towns  and 
small  cities.  Having  to  carry  the  pails  through  the  house 
or  yard  to  the  street  is  an  objection.  It  is  now  being  tried 
on  a large  scale  in  New  Orleans,  where  the  water  system 
cannot  be  readily  used. 

All  of  our  cities  and  towns  can  introdiicethis  system  with 
such  a small  outlay  of  capital,  that  it  would  seem  to  be  the 
one  just  now  to  be  most  highly  recommended. 

The  corporation  should  bear  the  expenses  of  the  transpor- 
tation of  the  excrernentitious  matter,  as  well  as  of  other  re- 
fuse and  filth  found  in  all  towns,  due  to  various  causes. 


*See  Appendix  II,  page  79. 


64 


SANITARY  ENGINEERING. 


THE  DRY  EARTH  SYSTEM. 

The  great  advantages  offered  by  the  “dry  earth  closet”  is 
well  known,  and  its  admirable  adaptability  to  the  sick  room. 

The  system  proposed  is  founded  on  this,  and  consists  in 
the  same  pails  used  in  the  preceding  system,  placed  in  dosed 
privies,  on  firm  and  dry  plank  or  concrete  foundation .*  The 
only  difference  is,  that  in  this  system  greater  care  is  used  in 
spreading  charcoal  or  dry  earth  over  the  night  soil,  so  as  to 
burn  it  up  as  quickly  as  possible,  and  that  the  pails  are 
emptied  in  a tight  vault  on  the  premises,  a little  earth  being 
thrown  on  top  of  the  emptied  mass,  to  keep  down  odor  and 
continue  the  work  of  exodation  to  completion. 

There  appeared  an  excellent  article  on  “ Village  Sanitary 
Work”  in  Scribners  for  June,  1877,  by  George  E.  Waring, 
Jr.  The  writer  says:  “In  the  autumn  of  1876,  I had 
brought  to  my  house,  where  only  earth  closets  are  used,  two 
small  cart  loads  of  garden  earth,  dried  and  sifted.  This  was 
used  repeatedly  in  the  closets,  and  when  an  increased  quan- 
tity was  required,  additions  were  made  of  sifted  anthracite 
ashes.  The  amount  of  material  now  on  hand  is  about  two 
toms,  which  is  ample  to  furnish  a supply  of  dry  and  decom- 
posed material  whenever  it  becomes  necessary  to  fill  the 
reservoirs  of  the  closets.  The  accumulation  under  the  seats 
is.  discharged  through  valves  into  brick  vaults  in  the  cellar. 
When  these  vaults  become  filled — about  three  times  in  a 
year — their  contents,  which  are  all  thoroughly  decomposed, 
are  piled  up  in  a dry  and  ventilated  place,  with  a slight 
covering  of  fresh  earth  to  keep  down  any  odor  that  might 
arise.  After  a sufficient  interval  these  heaps  are  ready  for 
further  use,  there  being  no  trace  in  any  portion  of  foreign 
matter  or  any  appearance  or  odor  differing  from  that  of  an 
unused  mixture  of  earth  and  ashes.  In  this  way  the  material 


See  Appendix  II,  pages  77,  and  78. 


WATER  SEWERAGE. 


65 


has  been  used  over  and  over  again,  at  least  ten  times*  and 
there  is  no  indication  to  the  sense  of  any  change  in  its  con- 
dition.” 

The  same  earth  can  be  used  over  and  over  again,  thus 
doing  away  with  what  was  once  urged  as  the  principle  ob- 
jection to  the  earth  closet  system — the  continual  removal  of 
large  bodies  of  earth. 

A chemical  analysis  showed  that  there  was  no  more  or- 
ganic matter  in  the  used  earth  than  in  fresh  earth,  thus 
proving  that  in  this  case  800  pounds  of  nitrogen,  etc.,  had 
gone  back  to  the  air  in  a harmless  state,  the  solid  organic 
matter  being  estimated  at  800  pounds,  of  which  some  230 
was  nitrogen. 

The  powerful  disinfecting  properties  of  charcoal  are  well 
known.  When  there  is  odor  about  a dead  body,  there  is 
nothing  better  than  carbon  in  some  of  its  forms  to  destroy  it. 
The  smoke  from  burning  tar,  coffee,  dried  apples,  etc.,  have 
all  been  successfully  tried. 

A covering  of  charcoal  will  preserve  tainted  flesh  of  any 
kind ; the  dog  instinctively  acts  upon  this  principle  when 
he  buries  a bone  in  the  earth  to  make  a repast  upon  some 
days  or  weeks  afterwards.  In  all  these  cases  it  is  not  the 
charcoal  or  earth,  but  the  oxygen  contained  in  its  pores  that 
destroys  the  odors  and  burns  up  the  substance. 

As  Mr.  Waring  says,  “ earth  is  not  to  be  regarded  as  a 
vehicle  for  the  inoffensive  removal  beyond  the  limits  of  the 
town  of  what  has  hitherto  been  its  most  troublesome  pro- 
duct, but  as  a medium  for  bringing  together  the  offensive 
ingredients  of  this  product  and  the  world’s  great  scavenger, 
oxygen.  This  oxygen  does  its  work  of  liberating  the  or- 
ganic elements  so  well  that,  according  to  Professor  Voelcker, 
“the  use  of  the  same  earth  four  or  five  times  over,  although 
perfectly  successful  in  accomplishing  the  chief  purpose  of 
deodorization,  fails  to  add  to  it  a sufficient  amount  of  fer- 
tilizing matter  to  make  it  an  available  commercial  manure.” 


5 


66 


SANITARY  ENGINEERING. 


This  agrees  with  the  analysis  previously  mentioned.  If 
the  earth  does  its  work  thoroughly,  the  manure  is  lost,  for, 
in  truth,  this  is  the  object  to  be  accomplished ; to  drive  the  or- 
ganic elements  back  again,  uncombined,  or  at  least  in  harm- 
less combinations,  to  the  air  ; and  this  the  condensed  oxygen 
accomplishes. 

One  advantage  of  the  system  is  that  the  privy  or  “ com- 
mode,” may  be  attached  to  the  house  ; in  fact  the  best  earth 
closets  may  be  kept  in  the  chamber,  without  any  other  odor 
being  perceived  than  that  of  the  earth  used,  which  should 
be  fine,  dry  and  sifted. 

This  dry  earth  system  is  familiar  to  soldiers  of  the  late 
war,  the  sinks  used  by  them  receiving  daily  a slight  cover- 
ing of  the  very  earth  thrown  out  in  their  construction. 
This  effectually  prevented  deleterious  effects ; and  in  exact 
accordance  with  the  theory  and  facts  previously  adduced, 
the  organic  matter  wTas  so  soon  dissipated — when  the  sys- 
tem was  carried  out  faithfully — that  the  earth  was  not  worth 
removal  as  manure.  This  fact  I know  from  experience; 
and  it  agrees  with  all  other  experiments  and  analyses  refer- 
ring to  this  point.  When  the  earth  covering  is  too  slight, 
or  it  is  neglected  at  times,  the  result  will  be  more  manure 
but  diminished  healthfulness.  There  can  be  no  hesitation 
in  the  choice. 

Where  the  dwelling  place  contains  a garden,  the  used  earth 
may  be  put  on  it,  for  it  is  quite  probable  that  even  when 
most,  or  all  of  the  organic  matter,  has  been  driven  off,  that 
the  chemical  changes  effected  may  have  liberated  potash  or 
soda,  etc.,  in  the  original  soil,  thus  rendering  it  more  valua- 
ble than  before  to  plants. 

It  may  be  interesting  to  know  that  there  is  biblical  sanc- 
tion for  this  method;  the  Israelites  being  required  to  carry 
out  the  system  whenever  they  went  outside  of  the  camp  to 
ease  themselves.  (Deut.,  xxiii:  13.) 

It  is  admitted  that  this  system  dees  not  admit  of  the  same 
public  control  as  the  preceding  ; but  it  may  be  made  emi- 


WATER  SEWERAGE. 


67 


nently  serviceable  by  those  who  desire  it.  It  is  especially 
applicable  to  country  houses  and  the  smaller  villages. 

1 know  of  this  system  being  carried  out  and  satisfying 
the  daily  wants  of  from  70  to  100  persons — the  room  being 
almost  entirely  free  from  odor  at  all  times.  If  sulphate 
of  lime  is  added,  it  fixes  the  ammonia  that  would  otherwise 
be  driven  off,  and  thus  renders  the  product  of  some  use  as 
a fertilizer. 

When  epidemics  prevail,  then  in  addition  to  usual  meth- 
ods of  sewage  disposal,  disinfectants  should  be  used,  as  to 
which  see  another  paper  issued  by  the  Board  of  Health  on 
the  subject. 


CONCLUSIONS. 


In  taking  a retrospective  glance  at  what  has  preceded,  we 
cannot  but  be  impressed  with  the  beneficence  of  those  laws 
that  tend,  in  one  eternal  round,  to  the  purification  of  what 
man  has  made  unclean.  Foul  sewage  is  thrown  into  a crys- 
tal stream,  whose  hitherto  transparent  waters  now  blush  at 
the  pollution.  She  invokes  the  aid  of  the  ever  constant 
winds  and  of  the  animal  and  vegetable  life  she  bears  in  her 
bosom.  They  respond,  and,  in  time,  she  is  once  more  pure 
and  undefiled.  The  pure  water  falls  from  clouds,  cleanses 
our  soil  and  passes  into  the  earth,  foul , to  again  issue  in 
wells  or  springs,  generally  free  from  the  taint  of  man’s 
works. 

Mother  earth  condenses  gases  that  oxidize  and  liberate 
noxious,  waste  elements  in  harmless  combinations.  We 
breathe  into  the  air  a hurtful  gas;  but  the  winds  and  the 
rains  bear  it  from  us,  or  the  vegetation  reaches  out  its  leaves, 
with  their  million  little  mouths,  to  absorb  it  and  give  us  in 
exchange  the  life  giving  oxygen. 

Is  it  asking  too  much,  should  Nature  call  sometimes  for 
man’s  assistance  to  expedite  results,  in  order  that  he  may 
add  to  his  days  and  happiness  ? If  not,  then  ponder  well 


68 


SANITARY  ENGINEERING. 


on  the  means  that  have  been  proposed  to  assist  nature  in 
her  work  of  purification,  and  act  on  them. 

It  is  not  intended  that  the  foregoing  brief  summary  of 
“means”  is  complete.  It  was  not  intended  to  be,  though 
fundamental  general  principles,  proper  to  be  known  at 
present,  it  is  hoped  have  been  stated  clearly  and  fairly. 

Burton  says  that  most  men  make  books  like  apothecaries 
make  medicine,  by  pouring  from  one  bottle  into  another. 
This  one  belongs  to  that  class — successful  experience  has 
been  inculcated  rather  than  novel  theories.  The  solutions 
used  have  been  standard  ones — often  huge  bottles  have  been 
poured  from,  even  the  crude  materials  of  the  still  have  been 
obtained  and  digested  before  using.  Most  of  the  elixirs 
mixed  beautifully,  forming  clear  solutions ; others  did  not, 
and  had  to  be  specially  treated  to  remove  the  antagonistic 
elements,  whilst  others  as  my  “ germ  ” bottle  would  not 
pour  at  all  scarcely,  the  fluid  being  dark  and  viscid. 

The  object  of  such  papers  as  this  is  to  advise  the  public, 
who  cannot  be  thinking  all  the  time  about  sanitary  matters, 
with  regard  to  efficient  means  of  protection  against  sickness, 
and  especially  against  epidemics.  The  county  boards  of 
health  are  looked  to  as  the  authorized  agents  in  introducing 
more  effective  sanitary  measures.  But  it  is  well  known  that 
such  organizations  cannot  go  far  ahead  of  public  opinion. 
We  need  the  aid  of  the  press,  the  great  educators  of  public 
opinion,  to  assist  in  the  good  fight  for  health. 

Let  srme  of  the  systems  for  the  disposal  of  sewage  matters 
be  faithfully  carried  out  simultaneously  with  a proper  at- 
tention to  ventilation,  drainage,  water  supply,  and  the  gene- 
ral cleanliness  of  streets  and  yards,  and  it  is  believed  that 
the  death  rate  will  be  lowered  and  that  epidemics  will  be 
almost  unknown. 

Let  every  open  privy  and  cess-pool  be  abolished  with  their 
pestilential  odors ; it  follows  that  the  source  of  contamina- 
tion of  the  wells  will  be  gone,  and  that  zymotic  diseases  will 
have  their  usual  channels  of  attack  effectually  cut  off. 


WATER  SEWERAGE. 


69 


Let  us,  then,  advance  towards  that  higher  civilization 
which  demands  pure  air  and  wholesome  water,  not  simply 
as  a luxury  to  be  enjoyed  only  on  the  cool  mountain’s  sides, 
but  as  a necessity,  to  be  enforced  in  city  and  village  by  strin- 
gent laws  and  requirements. 


APPENDIX  I. 


The  following  table  may  prove  a convenience  to  those 
who  use  cisterns.  It  gives  the  capacity  of  a cylindrical  cis- 
tern, for  one  toot  in  height,  and  the  diameters  given,  in  U. 
S.  liquid  gallons  (of  231  cubic  inches  each),  the  nearest 
whole  number  being  taken  : 


Diameter. 

Feet. 

Capacity. 

Gallons. 

Diameter. 

Feet. 

Capacity. 

Gallons. 

5 

147 

15 

1322 

6 

211 

16 

1504 

7 

288 

17 

1698 

8 

376 

18 

1903 

9 

476 

19 

2121 

10 

587 

20 

2350 

11 

711 

21 

2591 

12 

846 

22 

2843 

13 

993 

23 

3108 

14 

1151 

24 

3384 

Multiply  these  tabular  numbers  by  the  height  of  the  cis- 
tern in  feet  to  get  the  capacity  of  a cistern  corresponding  to 
that  height. 


APPENDIX  II 


Through  the  courtesy  of  Dr.  Charles  F.  Folsom,  of  the 
Massachusetts  Board  of  Health,  the  accompanying  wood 
cuts  are  presented — they  having  first  appeared  in  the  Mas- 
sachusetts Report  of  the  Board  of  Health  for  1876. 

The  cuts  represent  in  order  the  natural  drainage  from 
open  privies  and  sinks,  into  wells  that  are  placed  too  near 
them  ; sections  of  common  privies  and  sink  hole,  both  pol- 
luting the  soil  around  them;  and  lastly,  three  plans  for  pri- 
vies based  upon  the  dry  earth  system. 

It  is  to  be  observed  with  respect  to  the  latter,  that  the 
conditions  are  simply  that  the  pails  used  be  completely  un- 
der cover  and  placed  upon  a dry  foundation,  so  that  no 
matter  from  the  pails  shall  ever  reach  the  ground  below 
them,  thereby  poisoning  the  air  with  its  effluvia  and  the 
wells  with  its  drainage. 

It  is  necessary  that  the  earth,  charcoal  or  ashes  be  kept  in 
a dry  place  and  under  cover,  the  most  convenient  place  be- 
ing an  apartment  just  to  the  rear  of  the  pails,  from  which 
it  can  be  readily  shovelled  into  the  pails  under  and  not 
through  the  seats  as  when  the  ashes  etc.,  are  kept  in  the  privy 
room  proper. 

An  ordinary  open  privy  can  generally  be  transformed  into 
one  closed  from  the  access  of  rain,  by  cutting  out  a space  in 
the  weather-boarding  of  the  back,  nearly  as  high  as  the  top 
of  the  seats,  and  replacing  this  boarding  by  a door  working 
on  vertical  or  horizontal  hinges,  as  shown  in  one  of  the  fig- 
ures. On  opening  this  door,  the  half  barrels  or  pails  can  be 
set  under  the  seats,  and  every  morning  charcoal,  etc.,  can 
be  thrown  over  the  contents  so  as  to  keep  down  all  odor. 
The  pails  should  be  set  upon  a plank  or  stone  foundation — 
at  least  upon  a few  blocks  or  bricks — to  elevate  them  a few 


74 


APPENDIX  II. 


inches  above  the  ground,  so  that  water  may  not  reach  them. 
As  the  pails  are  filled  they  should  be  emptied  under  a shed 
and  dry  earth,  etc.,  strewn  over  the  contents,  the  action  of 
which  in  destroying  the  organic  matter  has  been  already 
explained. 

Where  wells  are  at  a distance,  the  contents  of  the  pails 
might  be  emptied  on  cultivated  ground  for  their  manure, 
a slight  covering  of  earth  being  again  used  to  keep  down 
any  odor  that  might  arise- 


APPENDIX  II. 


75 


76 


APPENDIX  II. 


APPENDIX  II. 


77 


Manchester  Corporation.. 
Di'yctsh  closet . Section 


Screens  to  separate  cinders 
fj:om  ash  and.  direct  the  latter 
onto  the  excrement. 


78 


APPENDIX  II, 


APPENDIX  II. 


79 


Rochdale  Corporation 
Pattern  Fail  closet. 


id.  excrement  pail . 

B. ash  tub. 

C.  seat  coyer  {raised) 

D iro  n collar  below  seat , reaching  slightly  into 
pail  when,  cover  is  dorm. 

F.  hinged  upright  of  seat 


APPENDIX  III. 


The  following  lucid  description  of  the  ventilation  of  the 
State  Lunatic  Asylum  of  New  York,  located  at  Utica,  N.  Y., 
is  taken,  by  permission  of  its  author,  Dr.  John  P.  Gray,  from 
the  “ Thirty-sixth  Annual  Report  of  the  Managers  of  the 
State  Lunatic  Asylum.” 

It  is  prefaced  by  a short  extract  from  the  report : 

“The  managers  consider  the  method  of  heating  and  ven- 
tilation of  the  institution  to  be  the  safest,  most  economical, 
and  best.  Information  is  frequently  sought  as  to  the  sys- 
tem adopted.  Recently  an  application  made  through  the 
State  Department  by  the  British  government  for  a detailed 
statement  concerning  the  appliances  and  method,  was  re- 
ferred to  Dr.  Gray,  the  superintendent  of  this  institution, 
who  made  a report  which  was  submitted  to  this  board  be- 
fore transmission.  The  managers  deem  it  such  a clear  and 
succinct  statement  of  the  method  adopted,  that  they  embody 
it  as  a document  worthy  of  permanent  record  for  use  and 
reference. 

Mode  of  Ventilating  and  Heating. 

1.  The  mode  of  ventilation  adopted  is  that  of  forcing  air 
into  the  building  by  the  use  of  two  centrifugal  fans,  a draw- 
ing and  description  of  which  accompany  this  communica- 
tion. 

2.  The  air  is  delivered  from  the  fans  to  all  parts  of  the 
building. 

3.  First : Into  the  large  channel  or  basement  air  duct, 
or  air  plenum,  which  is  continuous  under  the  whole  build- 
ing. 


6 


82 


APPENDIX  III. 


4.  Second : From  this  air  duct  or  air  plenum,  the  air 
passes  by  flues  into  the  various  wards  and  rooms  to  be  sup- 
olied.  Each  flue  is  independent ; that  is,  it  has  an  exit  at  but 
pne  point.  These  flues  open  into  the  wards  or  rooms  to  be 
supplied  at  a point  above  the  level  of  the  top  of  the  windows 
and  doors,  so  that  no  air  movement  caused  by  opening  a 
window  or  door  will  disturb  the  current  of  the  incoming  air. 
The  air  is  thus  distributed  uniformly  through  every  part  of 
the  building. 

5.  From  the  corridors  and  rooms  flues  are  constructed, 
starting  just  above  the  base-board,  each  flue  passing  inde- 
pendently into  the  attic  air  chamber.  Over  part  of  the 
building  theie  is  ridge  ventilation.  Over  other  parts  of  the 
building  the  exit  is  through  ventilators  fixed  at  regular 
distances. 

6.  Each  fan  delivers  at  each  revolution  1,000  cubic  feet 
of  air.  They  can  be  driven  to  supply  almost  any  desired 
quantity.  They  are  here  driven  night  and  day,  and  supply 
5,000,000  cubic  feet  of  air  per  hour,  which  is  a little  over 
100  cubic  feet  per  minute  to  each  occupant  of  the  house 
night  and  day. 

7.  The  main  air  duct  or  plenum  is  large  enough  to  con- 
tain any  quantity  of  air  desired,  without  the  need  of  a rapid 
current.  The  area  of  the  flues  leading  from  this  duct  to  the 
wards  and  rooms  is  equal  to  forty-two  inches  for  each  occu- 
pant. The  exit  flues  from  the  wards  and  rooms  to  the  attic 
chamber  is  equal  to  sixty-four  inches  for  each  occupant. 
The  exit  area  through  the  ridge  ventilation  and  ventilators 
equals  seventy  inches  for  each  occupant. 

8.  In  every  single  sleeping  room  there  is  a flue  for  the 
exit  of  air  of  sixty-four  inches  area.  In  associate  sleeping 
rooms  the  area  of  the  several  flues  is  equal  to  sixty-four  inches 
for  each  occupant.  The  flues  for  the  supply  of  air  open  on 
the  corridors  at  the  height  already  stated.  The  sleeping 
rooms  receive  the  air  from  the  corridors  at  or  near  the  floor. 


APPENDIX  III. 


83 


In  some  of  the  wards  there  is  no  threshold  under  the  door, 
and  the  doors  are  shortened  at  the  bottom  to  allow  a space 
between  them  and  the  floor  of  sixty-four  inches  area.  In  some 
the  air  enters  the  sleeping  rooms  through  a register  in  the 
bottom  rail  of  the  door.  In  the  associate  sleeping  rooms, 
where  sufficient  air  could  not  thus  be  obtained  for  several 
patients,  openings  are  made  through  the  walls  at  points  near 
the  floor.  In  a few  of  the  rooms  for  the  feeble  the  flues  for 
the  supply  of  air  open  into  the  rooms. 

9.  This  mode  secures  the  most  abundant  supply  of  fresh 
air.  It  secures  what  ventilation  means  practically  : that  is, 
such  constant  dilution  of  the  body  of  the  air  contained  in  the 
building  by  fresh  air  sent  in  as  to  make  it  for  all  practical 
purposes  pure. 

10.  I do  not  use  the  words  “ fresh  and  foul  air  flues.”  In 
reality,  this  method  secures  a constant  flow  of  pure  air 
through  the  building  from  its  entrance  to  its  exit,  and  the 
gradual  enlargement  of  the  areas  facilitates  the  passage  and 
exit  of  the  air,  and  compensates  for  the  frictional  resistance 
in  passing  through  the  building. 

11.  It  is  stated  in  paragraph  four  that  the  air  is  intro- 
duced at  a height  above  the  doors  and  windows.  While 
this  is  undoubtedly  best,  it  is  not  absolutely  necessary  to 
success  in  ventilation.  It  is  proper  to  say  that  in  a hospital 
for  the  insane,  it  is  advisable  to  have  the  air  enter  above  a 
point  where  patients  would  be  likely  to  throw  articles  into 
the  flues,  and  also  to  avoid  the  evil  of  patients  crowding 
about  the  flues  and  impeding  the  thorough  distributions  of 
the  air.  In  the  offices  of  the  institution,  in  the  residence  of 
the  officers,  and  some  of  the  rooms  not  constantly  used  in 
the  hospital  proper,  the  air  is  introduced  just  above  the  base- 
board, and  in  some  instances  through  the  floor ; but  in  all 
cases,  no  matter  where  the  air  is  introduced,  the  exit  flues 
should  start  from  near  the  floor  as  already  described.  Where 
the  air  is  thus  introduced,  it  is  important  to  locate  the  flues 
so  as  not  to  have  them  opposite  windows. 


84 


APPENDIX  III. 


12.  Where  the  rooms  are  large,  as  in  case  of  parlors  and 
sitting  rooms,  and  require  two  or  more  flues  for  the  intro- 
duction and  exit  of  air,  it  is  important  to  distribute  them  so 
that  all  parts  of  the  rooms  shall  be  supplied  uniformly. 

13.  Heating  is  combined  with  ventilation.  The  air  is 
warmed  to  the  degree  required  by  being  compelled  to  pass 
over  cast  iron  radiators,  through  which  steam  is  circulated, 
on  its  way  from  the  fan  to  the  occupied  parts  of  the  build- 
ing. These  radiators  are  placed  in  the  main  air  duct  or 
plenum,  and  are  in  separate  blocks  directly  underneath  the 
flues  leading  from  this  duct  to  the  occupied  parts  of  the 
building.  There  is  a box  of  radiators  for  each  set  of  three 
flues,  one  flue  leading  to  each  story.  Each  block  has  an  in- 
dependent connection  with  the  main  steam  pipe,  so  that 
each  block  can  be  used  separately.  Each  block  is  cased  in 
on  the  sides  leaving  the  bottom  open  for  the  free  passage  of 
air  over  the  radiators.  By  this  arrangement  the  air  is 
warmed  at  the  nearest  point  of  its  delivery  for  use,  and  the 
heat  is  not  wasted  b\r  absorption  into  the  walls  of  a large 
general  air  chamber,  and  the  temperature  of  the  air  sent 
into  any  special  part  of  the  building  can  be  regulated  as 
may  be  desired,  simply  by  introducing  more  or  less  steam 
into  the  individual  blocks. 

14.  These  radiators  are  so  constructed  and  connected  as 
to  make  what  is  called  a “ steam  coil,”  and  the  blocks  are 
so  arranged  and  connected  that  steam  can  be  turned  upon 
one-third,  two-thirds,  or  the  whole,  as  the  atmospheric  tem- 
perature may  require.  Of  course,  there  is  no  impediment 
to  the  passage  of  the  air  through  these  blocks  for  summer 
ventilation  when  heat  is  not  needed,  as  the  space  between 
them  is  sufficient  for  the  passage  of  the  largest  volume  of 
air  required. 

15.  This  large  body  of  air  entering  and  distributed  in  the 
manner  described  produces  no  appreciable  current.  It  is 
not  found  necessary  to  raise  the  temperature  of  the  air  in- 
troduced higher  than  100  degrees  at  the  point  of  entrance 


APPENDIX  III. 


85 


to  the  wards  and  rooms,  in  order  to  secure  a general  tempe- 
rature of  seventy  degrees  throughout.  Thus  the  air  is  not 
rarified,  expanded,  or  dried,  to  a degree  that  interferes  with 
healthfulness  and  comfort. 

16.  This  system  does  not  require  registers  to  control  the 
temperature  of  the  room  by  closing  and  unclosing  them. 
The  amount  of  air  delivered  over  each  radiating  block  is 
warmed  to  the  temperature  there  required,  and  as  the  vol- 
ume of  the  air  delivered  is  uniform  and  constant,  thorough 
ventilation  is  obtained.  Registers  in  the  wards  of  a hos- 
pital would  be  likely  to  be  used  to  close  off  the  flow  of  air  if 
it  was  too  warm,  that  being  easier  done  than  to  give  infor- 
mation to  the  engineer  having  control  of  the  heating  blocks. 
Registers  are  used  in  the  offices  and  residences  of  the  officers. 

17.  It  is  possible  to  determine  the  exact  amount  of  coal 
necessary  to  raise  a given  amount  of  atmosphere  one  degree, 
and  this  gives  the  key  to  the  necessary  amount  of  coal  to  be 
burned  in  the  steam  boilers  to  raise  the  whole  quantity  of 
air  introduced  to  any  desired  temperature.  The  engineer 
by  observing  the  temperature  of  the  external  atmosphere, 
and  knowing  the  volume  of  air  delivered,  can,  with  suffi- 
cient accuracy,  supply  the  necessary  amount  of  heat. 

18.  To  illustrate : The  cubic  capacity  of  the  wards  and 
rooms  of  this  asylum  is,  in  round  numbers,  about  5,000,000 
feet.  Five  million  cubic  feet  of  air  sent  in  by  the  fans  per 
hour  night  and  day.  Twelve  pounds  of  coal  will  raise  this 
atmosphere  one  degree  per  hour.  At  this  writing  the  aver- 
age outside  temperature  for  the  past  twenty-four  hours  has 
been  ten  degrees  below  zero.  The  temperature  of  the  wards 
has  been  maintained  at  from  seventy  to  seventy-two,  and  we 
have  burned  8 tons  and  1,280  pounds  of  coal,  an  average  of 
720  pounds  per  hour;  the  actual  number  of  occupants  722. 

DESCRIPTION  OF  FAN. 

The  fan  and  its  support  are  of  iron,  the  casing  of  wood 


86 


APPENDIX  III. 


the  rotary  or  operating  part  of  the  fan  consists  of  a 
shaft  with  eight  radial  arms  set  back  on  a curve  at  the 
extremities  of  which  are  fastened  iron  wind  boards, 
three  feet  wide  and  five  feet  long,  in  the  direction  of 
the  axis;  the  extremities  of  the  wind  boards  are  six  feet 
from  the  center  and  consequently  describe  a circle  of  twelve 
feet  diamter.  The  shaft  extends  beyond  the  casing  and 
rests  on  pulley  blocks,  and  on  the  driving  side  it  is  length- 
ened six  feet  to  receive  the  driving  pulle}'  and  remove  all 
obstruction  to  the  easy  entrance  of  air  to  the  fans ; the  mo- 
tion is  imparted  by  a belt  passing  over  the  pulley,  four  feet 
in  diameter,  with  ten-inch  face,  on  the  end  of  the  shaft,  the 
arms  and  boards  revolve  within  the  wooden  casing,  the  cir- 
cumference of  which  instead  of  being  concentric  with  the 
shaft,  describes  a curve  of  increasing  diameter  and  forms 
outside  the  wind  boards  a channel  of  constantly  enlarging 
capacity  towards  the  point  of  delivery.  The  casing  is  there- 
fore scroll-shaped,  this  space  being  six  inches  in  front  and 
enlarging  to  three  feet  at  the  bottom.  The  height  of  the 
casing  from  the  floor  is  eighteen  feet.  The  cross-sectional 
area  is  equal  at  the  point  of  delivery  to  forty-two  square 
feet.  The  opening  in  each  side  of  the  fan -casing,  for  the 
inlet  of  air,  is  six  feet  in  area.  This  whole  machinery  is 
placed  in  a room,  the  floor  of  which  is  on  a level  with  the 
floor  of  the  main  air  duct,  and  the  air  is  admitted  through 
a large  open  space,  double  the  area  of  both  inlets,  and 
properly  guarded. 


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